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vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Magnitude_scales"> <div class="vector-toc-text"> <span class="vector-toc-numb">2</span> <span>Magnitude scales</span> </div> </a> <button aria-controls="toc-Magnitude_scales-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle Magnitude scales subsection</span> </button> <ul id="toc-Magnitude_scales-sublist" class="vector-toc-list"> <li id="toc-"Richter"_magnitude_scale" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#"Richter"_magnitude_scale"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.1</span> <span>"Richter" magnitude scale</span> </div> </a> <ul id="toc-"Richter"_magnitude_scale-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Other_"local"_magnitude_scales" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Other_"local"_magnitude_scales"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.2</span> <span>Other "local" magnitude scales</span> </div> </a> <ul id="toc-Other_"local"_magnitude_scales-sublist" class="vector-toc-list"> <li id="toc-Japan_Meteorological_Agency_magnitude_scale" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Japan_Meteorological_Agency_magnitude_scale"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.2.1</span> <span>Japan Meteorological Agency magnitude scale</span> </div> </a> <ul id="toc-Japan_Meteorological_Agency_magnitude_scale-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Body-wave_magnitude_scales" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Body-wave_magnitude_scales"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.3</span> <span>Body-wave magnitude scales</span> </div> </a> <ul id="toc-Body-wave_magnitude_scales-sublist" class="vector-toc-list"> <li id="toc-mB_scale" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#mB_scale"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.3.1</span> <span>mB scale</span> </div> </a> <ul id="toc-mB_scale-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-mb_scale_2" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#mb_scale_2"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.3.2</span> <span>mb scale</span> </div> </a> <ul id="toc-mb_scale_2-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-mbLg_scale" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#mbLg_scale"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.3.3</span> <span>mb<sub>Lg</sub> scale</span> </div> </a> <ul id="toc-mbLg_scale-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Surface-wave_magnitude_scales" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Surface-wave_magnitude_scales"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.4</span> <span>Surface-wave magnitude scales</span> </div> </a> <ul id="toc-Surface-wave_magnitude_scales-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Moment_magnitude_and_energy_magnitude_scales" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Moment_magnitude_and_energy_magnitude_scales"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.5</span> <span>Moment magnitude and energy magnitude scales</span> </div> </a> <ul id="toc-Moment_magnitude_and_energy_magnitude_scales-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Energy_class_(K-class)_scale" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Energy_class_(K-class)_scale"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.6</span> <span>Energy class (<i>K</i>-class) scale</span> </div> </a> <ul id="toc-Energy_class_(K-class)_scale-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Tsunami_magnitude_scales" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Tsunami_magnitude_scales"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.7</span> <span>Tsunami magnitude scales</span> </div> </a> <ul id="toc-Tsunami_magnitude_scales-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Duration_and_coda_magnitude_scales" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Duration_and_coda_magnitude_scales"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.8</span> <span>Duration and coda magnitude scales</span> </div> </a> <ul id="toc-Duration_and_coda_magnitude_scales-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Macroseismic_magnitude_scales" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Macroseismic_magnitude_scales"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.9</span> <span>Macroseismic magnitude scales</span> </div> </a> <ul id="toc-Macroseismic_magnitude_scales-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Other_magnitude_scales" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Other_magnitude_scales"> <div class="vector-toc-text"> <span class="vector-toc-numb">2.10</span> <span>Other magnitude scales</span> </div> </a> <ul id="toc-Other_magnitude_scales-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-See_also" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#See_also"> <div class="vector-toc-text"> <span class="vector-toc-numb">3</span> <span>See also</span> </div> </a> <ul id="toc-See_also-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Citations" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Citations"> <div class="vector-toc-text"> <span class="vector-toc-numb">4</span> <span>Citations</span> </div> </a> <ul id="toc-Citations-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-General_and_cited_sources" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#General_and_cited_sources"> <div class="vector-toc-text"> <span class="vector-toc-numb">5</span> <span>General and cited sources</span> </div> </a> <ul id="toc-General_and_cited_sources-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-External_links" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#External_links"> <div class="vector-toc-text"> <span class="vector-toc-numb">6</span> <span>External links</span> </div> </a> <ul id="toc-External_links-sublist" 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Available in 26 languages" > <label id="p-lang-btn-label" for="p-lang-btn-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--action-progressive mw-portlet-lang-heading-26" aria-hidden="true" ><span class="vector-icon mw-ui-icon-language-progressive mw-ui-icon-wikimedia-language-progressive"></span> <span class="vector-dropdown-label-text">26 languages</span> </label> <div class="vector-dropdown-content"> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li class="interlanguage-link interwiki-az mw-list-item"><a href="https://az.wikipedia.org/wiki/Maqnituda" title="Maqnituda – Azerbaijani" lang="az" hreflang="az" data-title="Maqnituda" data-language-autonym="Azərbaycanca" data-language-local-name="Azerbaijani" class="interlanguage-link-target"><span>Azərbaycanca</span></a></li><li class="interlanguage-link interwiki-be mw-list-item"><a href="https://be.wikipedia.org/wiki/%D0%9C%D0%B0%D0%B3%D0%BD%D1%96%D1%82%D1%83%D0%B4%D0%B0_%D0%B7%D0%B5%D0%BC%D0%BB%D0%B5%D1%82%D1%80%D0%B0%D1%81%D0%B5%D0%BD%D0%BD%D1%8F" title="Магнітуда землетрасення – Belarusian" lang="be" hreflang="be" data-title="Магнітуда землетрасення" data-language-autonym="Беларуская" data-language-local-name="Belarusian" class="interlanguage-link-target"><span>Беларуская</span></a></li><li class="interlanguage-link interwiki-bg mw-list-item"><a href="https://bg.wikipedia.org/wiki/%D0%9C%D0%B0%D0%B3%D0%BD%D0%B8%D1%82%D1%83%D0%B4" title="Магнитуд – Bulgarian" lang="bg" hreflang="bg" data-title="Магнитуд" data-language-autonym="Български" data-language-local-name="Bulgarian" class="interlanguage-link-target"><span>Български</span></a></li><li class="interlanguage-link interwiki-bar mw-list-item"><a href="https://bar.wikipedia.org/wiki/Magnitudn_(Erdbem)" title="Magnitudn (Erdbem) – Bavarian" lang="bar" hreflang="bar" data-title="Magnitudn (Erdbem)" data-language-autonym="Boarisch" data-language-local-name="Bavarian" class="interlanguage-link-target"><span>Boarisch</span></a></li><li class="interlanguage-link interwiki-cs mw-list-item"><a href="https://cs.wikipedia.org/wiki/Magnitudo" title="Magnitudo – Czech" lang="cs" hreflang="cs" data-title="Magnitudo" data-language-autonym="Čeština" data-language-local-name="Czech" class="interlanguage-link-target"><span>Čeština</span></a></li><li class="interlanguage-link interwiki-de mw-list-item"><a href="https://de.wikipedia.org/wiki/Magnitude_(Erdbeben)" title="Magnitude (Erdbeben) – German" lang="de" hreflang="de" data-title="Magnitude (Erdbeben)" data-language-autonym="Deutsch" data-language-local-name="German" class="interlanguage-link-target"><span>Deutsch</span></a></li><li class="interlanguage-link interwiki-et mw-list-item"><a href="https://et.wikipedia.org/wiki/Maav%C3%A4rina_magnituud" title="Maavärina magnituud – Estonian" lang="et" hreflang="et" data-title="Maavärina magnituud" data-language-autonym="Eesti" data-language-local-name="Estonian" class="interlanguage-link-target"><span>Eesti</span></a></li><li class="interlanguage-link interwiki-es mw-list-item"><a href="https://es.wikipedia.org/wiki/Escalas_de_magnitud_s%C3%ADsmica" title="Escalas de magnitud sísmica – Spanish" lang="es" hreflang="es" data-title="Escalas de magnitud sísmica" data-language-autonym="Español" data-language-local-name="Spanish" class="interlanguage-link-target"><span>Español</span></a></li><li class="interlanguage-link interwiki-eo mw-list-item"><a href="https://eo.wikipedia.org/wiki/Magnitudo_(tertremo)" title="Magnitudo (tertremo) – Esperanto" lang="eo" hreflang="eo" data-title="Magnitudo (tertremo)" data-language-autonym="Esperanto" data-language-local-name="Esperanto" class="interlanguage-link-target"><span>Esperanto</span></a></li><li class="interlanguage-link interwiki-fa badge-Q17437798 badge-goodarticle mw-list-item" title="good article badge"><a href="https://fa.wikipedia.org/wiki/%D9%85%D9%82%DB%8C%D8%A7%D8%B3%E2%80%8C%D9%87%D8%A7%DB%8C_%D8%A8%D8%B2%D8%B1%DA%AF%DB%8C_%D9%84%D8%B1%D8%B2%D9%87%E2%80%8C%D8%A7%DB%8C" title="مقیاس‌های بزرگی لرزه‌ای – Persian" lang="fa" hreflang="fa" data-title="مقیاس‌های بزرگی لرزه‌ای" data-language-autonym="فارسی" data-language-local-name="Persian" class="interlanguage-link-target"><span>فارسی</span></a></li><li class="interlanguage-link interwiki-fr mw-list-item"><a href="https://fr.wikipedia.org/wiki/Magnitude_(sismologie)" title="Magnitude (sismologie) – French" lang="fr" hreflang="fr" data-title="Magnitude (sismologie)" data-language-autonym="Français" data-language-local-name="French" class="interlanguage-link-target"><span>Français</span></a></li><li class="interlanguage-link interwiki-ko mw-list-item"><a href="https://ko.wikipedia.org/wiki/%EC%A7%80%EC%A7%84_%EA%B7%9C%EB%AA%A8" title="지진 규모 – Korean" lang="ko" hreflang="ko" data-title="지진 규모" data-language-autonym="한국어" data-language-local-name="Korean" class="interlanguage-link-target"><span>한국어</span></a></li><li class="interlanguage-link interwiki-id mw-list-item"><a href="https://id.wikipedia.org/wiki/Skala_kekuatan_seismik" title="Skala kekuatan seismik – Indonesian" lang="id" hreflang="id" data-title="Skala kekuatan seismik" data-language-autonym="Bahasa Indonesia" data-language-local-name="Indonesian" class="interlanguage-link-target"><span>Bahasa Indonesia</span></a></li><li class="interlanguage-link interwiki-is mw-list-item"><a href="https://is.wikipedia.org/wiki/Jar%C3%B0skj%C3%A1lftakvar%C3%B0ar" title="Jarðskjálftakvarðar – Icelandic" lang="is" hreflang="is" data-title="Jarðskjálftakvarðar" data-language-autonym="Íslenska" data-language-local-name="Icelandic" class="interlanguage-link-target"><span>Íslenska</span></a></li><li class="interlanguage-link interwiki-it mw-list-item"><a href="https://it.wikipedia.org/wiki/Magnitudo" title="Magnitudo – Italian" lang="it" hreflang="it" data-title="Magnitudo" data-language-autonym="Italiano" data-language-local-name="Italian" class="interlanguage-link-target"><span>Italiano</span></a></li><li class="interlanguage-link interwiki-la mw-list-item"><a href="https://la.wikipedia.org/wiki/Magnitudo" title="Magnitudo – Latin" lang="la" hreflang="la" data-title="Magnitudo" data-language-autonym="Latina" data-language-local-name="Latin" class="interlanguage-link-target"><span>Latina</span></a></li><li class="interlanguage-link interwiki-ja mw-list-item"><a href="https://ja.wikipedia.org/wiki/%E3%83%9E%E3%82%B0%E3%83%8B%E3%83%81%E3%83%A5%E3%83%BC%E3%83%89" title="マグニチュード – Japanese" lang="ja" hreflang="ja" data-title="マグニチュード" data-language-autonym="日本語" data-language-local-name="Japanese" class="interlanguage-link-target"><span>日本語</span></a></li><li class="interlanguage-link interwiki-nds mw-list-item"><a href="https://nds.wikipedia.org/wiki/Magnitude_(Seismologie)" title="Magnitude (Seismologie) – Low German" lang="nds" hreflang="nds" data-title="Magnitude (Seismologie)" data-language-autonym="Plattdüütsch" data-language-local-name="Low German" class="interlanguage-link-target"><span>Plattdüütsch</span></a></li><li class="interlanguage-link interwiki-pt mw-list-item"><a href="https://pt.wikipedia.org/wiki/Magnitude_s%C3%ADsmica" title="Magnitude sísmica – Portuguese" lang="pt" hreflang="pt" data-title="Magnitude sísmica" data-language-autonym="Português" data-language-local-name="Portuguese" class="interlanguage-link-target"><span>Português</span></a></li><li class="interlanguage-link interwiki-scn mw-list-item"><a href="https://scn.wikipedia.org/wiki/Magnit%C3%B9dini_(giolugg%C3%ACa)" title="Magnitùdini (gioluggìa) – Sicilian" lang="scn" hreflang="scn" data-title="Magnitùdini (gioluggìa)" data-language-autonym="Sicilianu" data-language-local-name="Sicilian" class="interlanguage-link-target"><span>Sicilianu</span></a></li><li class="interlanguage-link interwiki-simple mw-list-item"><a href="https://simple.wikipedia.org/wiki/Seismic_magnitude_scales" title="Seismic magnitude scales – Simple English" lang="en-simple" hreflang="en-simple" data-title="Seismic magnitude scales" data-language-autonym="Simple English" data-language-local-name="Simple English" class="interlanguage-link-target"><span>Simple English</span></a></li><li class="interlanguage-link interwiki-sk mw-list-item"><a href="https://sk.wikipedia.org/wiki/Magnit%C3%BAdo" title="Magnitúdo – Slovak" lang="sk" hreflang="sk" data-title="Magnitúdo" data-language-autonym="Slovenčina" data-language-local-name="Slovak" class="interlanguage-link-target"><span>Slovenčina</span></a></li><li class="interlanguage-link interwiki-fi mw-list-item"><a href="https://fi.wikipedia.org/wiki/Magnitudi_(seismologia)" title="Magnitudi (seismologia) – Finnish" lang="fi" hreflang="fi" data-title="Magnitudi (seismologia)" data-language-autonym="Suomi" data-language-local-name="Finnish" class="interlanguage-link-target"><span>Suomi</span></a></li><li class="interlanguage-link interwiki-ta mw-list-item"><a href="https://ta.wikipedia.org/wiki/%E0%AE%A8%E0%AE%BF%E0%AE%B2%E0%AE%A8%E0%AE%9F%E0%AF%81%E0%AE%95%E0%AF%8D%E0%AE%95_%E0%AE%85%E0%AE%B3%E0%AE%B5%E0%AF%80%E0%AE%9F%E0%AF%81" title="நிலநடுக்க அளவீடு – Tamil" lang="ta" hreflang="ta" data-title="நிலநடுக்க அளவீடு" data-language-autonym="தமிழ்" data-language-local-name="Tamil" class="interlanguage-link-target"><span>தமிழ்</span></a></li><li class="interlanguage-link interwiki-uk mw-list-item"><a href="https://uk.wikipedia.org/wiki/%D0%A8%D0%BA%D0%B0%D0%BB%D0%B8_%D1%81%D0%B5%D0%B9%D1%81%D0%BC%D1%96%D1%87%D0%BD%D0%B8%D1%85_%D0%BC%D0%B0%D0%B3%D0%BD%D1%96%D1%82%D1%83%D0%B4" title="Шкали сейсмічних магнітуд – Ukrainian" lang="uk" hreflang="uk" data-title="Шкали сейсмічних магнітуд" data-language-autonym="Українська" data-language-local-name="Ukrainian" class="interlanguage-link-target"><span>Українська</span></a></li><li class="interlanguage-link interwiki-zh mw-list-item"><a href="https://zh.wikipedia.org/wiki/%E5%9C%B0%E9%9C%87%E5%BA%A6%E9%87%8F" title="地震度量 – Chinese" lang="zh" hreflang="zh" data-title="地震度量" data-language-autonym="中文" data-language-local-name="Chinese" class="interlanguage-link-target"><span>中文</span></a></li> </ul> <div class="after-portlet after-portlet-lang"><span class="wb-langlinks-edit wb-langlinks-link"><a href="https://www.wikidata.org/wiki/Special:EntityPage/Q500062#sitelinks-wikipedia" title="Edit interlanguage links" class="wbc-editpage">Edit links</a></span></div> </div> </div> </div> </header> <div class="vector-page-toolbar"> <div class="vector-page-toolbar-container"> <div id="left-navigation"> <nav aria-label="Namespaces"> <div id="p-associated-pages" class="vector-menu vector-menu-tabs mw-portlet mw-portlet-associated-pages" > <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="ca-nstab-main" class="selected vector-tab-noicon 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a{color:var(--color-progressive)!important}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .sidebar:not(.notheme) .sidebar-list-title,html.skin-theme-clientpref-os .mw-parser-output .sidebar:not(.notheme) .sidebar-title-with-pretitle{background:transparent!important}html.skin-theme-clientpref-os .mw-parser-output .sidebar:not(.notheme) .sidebar-title-with-pretitle a{color:var(--color-progressive)!important}}@media print{body.ns-0 .mw-parser-output .sidebar{display:none!important}}</style><table class="sidebar sidebar-collapse nomobile nowraplinks"><tbody><tr><td class="sidebar-pretitle">Part of <a href="/wiki/Category:Earthquakes" title="Category:Earthquakes">a series</a> on</td></tr><tr><th class="sidebar-title-with-pretitle"><a href="/wiki/Earthquake" title="Earthquake">Earthquakes</a></th></tr><tr><td class="sidebar-image"><span typeof="mw:File"><a href="/wiki/File:Earthquake_-_The_Noun_Project.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/a/a0/Earthquake_-_The_Noun_Project.svg/80px-Earthquake_-_The_Noun_Project.svg.png" decoding="async" width="80" height="64" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/a/a0/Earthquake_-_The_Noun_Project.svg/120px-Earthquake_-_The_Noun_Project.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/a/a0/Earthquake_-_The_Noun_Project.svg/160px-Earthquake_-_The_Noun_Project.svg.png 2x" data-file-width="512" data-file-height="410" /></a></span></td></tr><tr><td class="sidebar-content"> <div class="sidebar-list mw-collapsible mw-collapsed"><div class="sidebar-list-title" style="color: var(--color-base)"><a href="/wiki/Types_of_earthquake" title="Types of earthquake">Types</a></div><div class="sidebar-list-content mw-collapsible-content hlist"> <ul><li><a href="/wiki/Mainshock" title="Mainshock">Mainshock</a></li> <li><a href="/wiki/Foreshock" title="Foreshock">Foreshock</a></li> <li><a href="/wiki/Aftershock" title="Aftershock">Aftershock</a></li> <li><a href="/wiki/Blind_thrust_earthquake" title="Blind thrust earthquake">Blind thrust</a></li> <li><a href="/wiki/Doublet_earthquake" title="Doublet earthquake">Doublet</a></li> <li><a href="/wiki/Interplate_earthquake" title="Interplate earthquake">Interplate</a></li> <li><a href="/wiki/Intraplate_earthquake" title="Intraplate earthquake">Intraplate</a></li> <li><a href="/wiki/Megathrust_earthquake" title="Megathrust earthquake">Megathrust</a></li> <li><a href="/wiki/Remotely_triggered_earthquakes" title="Remotely triggered earthquakes">Remotely triggered</a></li> <li><a href="/wiki/Slow_earthquake" title="Slow earthquake">Slow</a></li> <li><a href="/wiki/Submarine_earthquake" title="Submarine earthquake">Submarine</a></li> <li><a href="/wiki/Supershear_earthquake" title="Supershear earthquake">Supershear</a></li> <li><a href="/wiki/Tsunami_earthquake" title="Tsunami earthquake">Tsunami</a></li> <li><a href="/wiki/Earthquake_swarm" title="Earthquake swarm">Earthquake swarm</a></li></ul></div></div></td> </tr><tr><td class="sidebar-content"> <div class="sidebar-list mw-collapsible mw-collapsed"><div class="sidebar-list-title" style="color: var(--color-base)">Causes</div><div class="sidebar-list-content mw-collapsible-content hlist"> <ul><li><a href="/wiki/Fault_(geology)" title="Fault (geology)">Fault movement</a></li> <li><a href="/wiki/Volcano_tectonic_earthquake" title="Volcano tectonic earthquake">Volcanism</a></li> <li><a href="/wiki/Induced_seismicity" title="Induced seismicity">Induced seismicity</a></li></ul></div></div></td> </tr><tr><td class="sidebar-content"> <div class="sidebar-list mw-collapsible mw-collapsed"><div class="sidebar-list-title" style="color: var(--color-base)">Characteristics</div><div class="sidebar-list-content mw-collapsible-content hlist"> <ul><li><a href="/wiki/Epicenter" title="Epicenter">Epicenter</a></li> <li><a href="/wiki/Epicentral_distance" title="Epicentral distance">Epicentral distance</a></li> <li><a href="/wiki/Hypocenter" title="Hypocenter">Hypocenter</a></li> <li><a href="/wiki/Shadow_zone" title="Shadow zone">Shadow zone</a></li> <li><a href="/wiki/Seismic_wave" title="Seismic wave">Seismic waves</a></li> <li><a href="/wiki/P_wave" title="P wave">P wave</a></li> <li><a href="/wiki/S_wave" title="S wave">S wave</a></li></ul></div></div></td> </tr><tr><td class="sidebar-content"> <div class="sidebar-list mw-collapsible mw-collapsed"><div class="sidebar-list-title" style="color: var(--color-base)">Measurement</div><div class="sidebar-list-content mw-collapsible-content hlist"> <ul><li><a href="/wiki/Seismometer" title="Seismometer">Seismometer</a></li> <li><a class="mw-selflink selflink">Seismic magnitude scales</a></li> <li><a href="/wiki/Seismic_intensity_scales" title="Seismic intensity scales">Seismic intensity scales</a></li></ul></div></div></td> </tr><tr><td class="sidebar-content"> <div class="sidebar-list mw-collapsible mw-collapsed"><div class="sidebar-list-title" style="color: var(--color-base)"><a href="/wiki/Earthquake_prediction" title="Earthquake prediction">Prediction</a></div><div class="sidebar-list-content mw-collapsible-content hlist"> <ul><li><div style="display:inline-block; padding:0.2em 0.4em; line-height:1.2em; line-height:1.25em;"><a href="/wiki/Coordinating_Committee_for_Earthquake_Prediction" title="Coordinating Committee for Earthquake Prediction">Coordinating Committee for<br />Earthquake Prediction</a></div></li> <li><a href="/wiki/Earthquake_forecasting" title="Earthquake forecasting">Forecasting</a></li></ul></div></div></td> </tr><tr><td class="sidebar-content"> <div class="sidebar-list mw-collapsible mw-collapsed"><div class="sidebar-list-title" style="color: var(--color-base)">Other topics</div><div class="sidebar-list-content mw-collapsible-content hlist"> <ul><li><a href="/wiki/Shear_wave_splitting" title="Shear wave splitting">Shear wave splitting</a></li> <li><a href="/wiki/Adams%E2%80%93Williamson_equation" title="Adams–Williamson equation">Adams–Williamson equation</a></li> <li><a href="/wiki/Flinn%E2%80%93Engdahl_regions" class="mw-redirect" title="Flinn–Engdahl regions">Flinn–Engdahl regions</a></li> <li><a href="/wiki/Earthquake_engineering" title="Earthquake engineering">Earthquake engineering</a></li> <li><a href="/wiki/Seismite" title="Seismite">Seismite</a></li> <li><a href="/wiki/Seismology" title="Seismology">Seismology</a></li></ul></div></div></td> </tr><tr><td class="sidebar-below hlist"> <ul><li><a href="/wiki/Portal:Earth_sciences" title="Portal:Earth sciences">Earth Sciences Portal</a></li></ul> <ul><li><a href="/wiki/Category:Earthquakes" title="Category:Earthquakes">Category</a></li> <li><a href="/wiki/Index_of_geology_articles" title="Index of geology articles">Related topics</a></li></ul></td></tr><tr><td class="sidebar-navbar" style="border-top:1px solid #aaa;"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><style data-mw-deduplicate="TemplateStyles:r1239400231">.mw-parser-output .navbar{display:inline;font-size:88%;font-weight:normal}.mw-parser-output .navbar-collapse{float:left;text-align:left}.mw-parser-output .navbar-boxtext{word-spacing:0}.mw-parser-output .navbar ul{display:inline-block;white-space:nowrap;line-height:inherit}.mw-parser-output .navbar-brackets::before{margin-right:-0.125em;content:"[ "}.mw-parser-output .navbar-brackets::after{margin-left:-0.125em;content:" ]"}.mw-parser-output .navbar li{word-spacing:-0.125em}.mw-parser-output .navbar a>span,.mw-parser-output .navbar a>abbr{text-decoration:inherit}.mw-parser-output .navbar-mini abbr{font-variant:small-caps;border-bottom:none;text-decoration:none;cursor:inherit}.mw-parser-output .navbar-ct-full{font-size:114%;margin:0 7em}.mw-parser-output .navbar-ct-mini{font-size:114%;margin:0 4em}html.skin-theme-clientpref-night .mw-parser-output .navbar li a abbr{color:var(--color-base)!important}@media(prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .navbar li a abbr{color:var(--color-base)!important}}@media print{.mw-parser-output .navbar{display:none!important}}</style><div class="navbar plainlinks hlist navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:Earthquakes" title="Template:Earthquakes"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:Earthquakes" title="Template talk:Earthquakes"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:Earthquakes" title="Special:EditPage/Template:Earthquakes"><abbr title="Edit this template">e</abbr></a></li></ul></div></td></tr></tbody></table> <p><b>Seismic magnitude scales</b> are used to describe the overall strength or "size" of an <a href="/wiki/Earthquake" title="Earthquake">earthquake</a>. These are distinguished from <a href="/wiki/Seismic_intensity_scales" title="Seismic intensity scales">seismic intensity scales</a> that categorize the intensity or severity of ground shaking (quaking) caused by an earthquake at a given location. Magnitudes are usually determined from measurements of an earthquake's <a href="/wiki/Seismic_wave" title="Seismic wave">seismic waves</a> as recorded on a <a href="/wiki/Seismogram" title="Seismogram">seismogram</a>. Magnitude scales vary based on what aspect of the seismic waves are measured and how they are measured. Different magnitude scales are necessary because of differences in earthquakes, the information available, and the purposes for which the magnitudes are used. </p> <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="Earthquake_magnitude_and_ground-shaking_intensity">Earthquake magnitude and ground-shaking intensity <span class="anchor" id="magnitude"></span></h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Seismic_magnitude_scales&action=edit&section=1" title="Edit section: Earthquake magnitude and ground-shaking intensity"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:1968_Illinois_earthquake.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/4/4e/1968_Illinois_earthquake.svg/350px-1968_Illinois_earthquake.svg.png" decoding="async" width="350" height="320" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/4/4e/1968_Illinois_earthquake.svg/525px-1968_Illinois_earthquake.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/4/4e/1968_Illinois_earthquake.svg/700px-1968_Illinois_earthquake.svg.png 2x" data-file-width="394" data-file-height="360" /></a><figcaption>Isoseismal map for the <a href="/wiki/1968_Illinois_earthquake" title="1968 Illinois earthquake">1968 Illinois earthquake</a>. The irregular distribution of shaking arises from variations of geology and/or ground conditions.</figcaption></figure> <p>The Earth's crust is stressed by <a href="/wiki/Tectonic" class="mw-redirect" title="Tectonic">tectonic</a> forces. When this stress becomes great enough to rupture the crust, or to overcome the friction that prevents one block of crust from slipping past another, energy is released, some of it in the form of various kinds of seismic waves that cause ground-shaking, or quaking. </p><p><i>Magnitude</i> is an estimate of the relative "size" or strength of an <i>earthquake</i>, and thus its potential for causing ground-shaking. It is "approximately related to the released seismic energy."<sup id="cite_ref-1" class="reference"><a href="#cite_note-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> </p><p><i>Intensity</i> refers to the strength or force of <i>shaking</i> at a given location, and can be related to the peak ground velocity. With an <a href="/wiki/Isoseismal_map" title="Isoseismal map">isoseismal map</a> of the observed intensities (see illustration) an earthquake's magnitude can be estimated from both the maximum intensity observed (usually but not always near the <a href="/wiki/Epicenter" title="Epicenter">epicenter</a>), and from the extent of the area where the earthquake was felt.<sup id="cite_ref-2" class="reference"><a href="#cite_note-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> </p><p>The intensity of local ground-shaking depends on several factors besides the magnitude of the earthquake,<sup id="cite_ref-3" class="reference"><a href="#cite_note-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> one of the most important being soil conditions. For instance, thick layers of soft soil (such as fill) can amplify seismic waves, often at a considerable distance from the source, while sedimentary basins will often resonate, increasing the duration of shaking. This is why, in the <a href="/wiki/1989_Loma_Prieta_earthquake" title="1989 Loma Prieta earthquake">1989 Loma Prieta earthquake</a>, the <a href="/wiki/Marina_District,_San_Francisco" title="Marina District, San Francisco">Marina district of San Francisco</a> was one of the most damaged areas, though it was nearly 100 km from the epicenter.<sup id="cite_ref-4" class="reference"><a href="#cite_note-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> Geological structures were also significant, such as where seismic waves passing under the south end of San Francisco Bay reflected off the base of the Earth's crust towards San Francisco and Oakland. A similar effect channeled seismic waves between the other major faults in the area.<sup id="cite_ref-5" class="reference"><a href="#cite_note-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Magnitude_scales">Magnitude scales</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Seismic_magnitude_scales&action=edit&section=2" title="Edit section: Magnitude scales"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:1906_San_Francisco_earthquake_seismograph.png" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/3/32/1906_San_Francisco_earthquake_seismograph.png/440px-1906_San_Francisco_earthquake_seismograph.png" decoding="async" width="440" height="332" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/3/32/1906_San_Francisco_earthquake_seismograph.png/660px-1906_San_Francisco_earthquake_seismograph.png 1.5x, //upload.wikimedia.org/wikipedia/commons/3/32/1906_San_Francisco_earthquake_seismograph.png 2x" data-file-width="674" data-file-height="508" /></a><figcaption>Typical seismogram. The compressive <a href="/wiki/P_waves" class="mw-redirect" title="P waves">P waves</a> (following the red lines) – essentially sound passing through rock – are the fastest seismic waves, and arrive first, typically in about 10 seconds for an earthquake around 50 km away. The sideways-shaking <a href="/wiki/S_waves" class="mw-redirect" title="S waves">S waves</a> (following the green lines) arrive some seconds later, traveling a little over half the speed of the P waves; the delay is a direct indication of the distance to the quake. S waves may take an hour to reach a point 1000 km away. Both of these are <i>body-waves</i>, that pass directly through the earth's crust. Following the S waves are various kinds of <i>surface-waves</i> – <a href="/wiki/Love_wave" title="Love wave">Love waves</a> and <a href="/wiki/Rayleigh_wave" title="Rayleigh wave">Rayleigh waves</a> – that travel only at the earth's surface. Surface waves are smaller for deep earthquakes, which have less interaction with the surface. For shallow earthquakes – less than roughly 60 km deep – the surface waves are stronger, and may last several minutes; these carry most of the energy of the quake, and cause the most severe damage.</figcaption></figure> <p>An earthquake radiates energy in the form of different kinds of <a href="/wiki/Seismic_wave" title="Seismic wave">seismic waves</a>, whose characteristics reflect the nature of both the rupture and the earth's crust the waves travel through.<sup id="cite_ref-6" class="reference"><a href="#cite_note-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> Determination of an earthquake's magnitude generally involves identifying specific kinds of these waves on a <a href="/wiki/Seismogram" title="Seismogram">seismogram</a>, and then measuring one or more characteristics of a wave, such as its timing, orientation, amplitude, frequency, or duration.<sup id="cite_ref-7" class="reference"><a href="#cite_note-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> Additional adjustments are made for distance, kind of crust, and the characteristics of the <a href="/wiki/Seismograph" class="mw-redirect" title="Seismograph">seismograph</a> that recorded the seismogram. </p><p>The various magnitude scales represent different ways of deriving magnitude from such information as is available. All magnitude scales retain the logarithmic scale as devised by <a href="/wiki/Charles_Richter" title="Charles Richter">Charles Richter</a>, and are adjusted so the mid-range approximately correlates with the original "Richter" scale.<sup id="cite_ref-8" class="reference"><a href="#cite_note-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup> </p><p>Most magnitude scales are based on measurements of only part of an earthquake's seismic wave-train, and therefore are incomplete. This results in systematic underestimation of magnitude in certain cases, a condition called <i>saturation</i>.<sup id="cite_ref-9" class="reference"><a href="#cite_note-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup> </p><p>Since 2005 the <a href="/wiki/IASPEI" class="mw-redirect" title="IASPEI">International Association of Seismology and Physics of the Earth's Interior</a> (IASPEI) has standardized the measurement procedures and equations for the principal magnitude scales, M<sub>L</sub> , M<sub>s</sub> , mb , mB  and mb<sub>Lg</sub> .<sup id="cite_ref-10" class="reference"><a href="#cite_note-10"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup> </p><p><span class="anchor" id="Local_magnitude_scale"></span><span class="anchor" id="Richter"></span><span class="anchor" id="ML"></span> </p> <div class="mw-heading mw-heading3"><h3 id=""Richter"_magnitude_scale"><span id=".22Richter.22_magnitude_scale"></span>"Richter" magnitude scale</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Seismic_magnitude_scales&action=edit&section=3" title="Edit section: "Richter" magnitude scale"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1236090951">.mw-parser-output .hatnote{font-style:italic}.mw-parser-output div.hatnote{padding-left:1.6em;margin-bottom:0.5em}.mw-parser-output .hatnote i{font-style:normal}.mw-parser-output .hatnote+link+.hatnote{margin-top:-0.5em}@media print{body.ns-0 .mw-parser-output .hatnote{display:none!important}}</style><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/Richter_magnitude_scale" class="mw-redirect" title="Richter magnitude scale">Richter magnitude scale</a></div> <p>The first scale for measuring earthquake magnitudes, developed in 1935 by <a href="/wiki/Charles_F._Richter" class="mw-redirect" title="Charles F. Richter">Charles F. Richter</a> and popularly known as the "Richter" scale, is actually the <style data-mw-deduplicate="TemplateStyles:r1238216509">.mw-parser-output .vanchor>:target~.vanchor-text{background-color:#b1d2ff}@media screen{html.skin-theme-clientpref-night .mw-parser-output .vanchor>:target~.vanchor-text{background-color:#0f4dc9}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .vanchor>:target~.vanchor-text{background-color:#0f4dc9}}</style><span class="vanchor"><span id="Local_magnitude_scale"></span><span class="vanchor-text">Local magnitude scale</span></span>, label <b>ML</b> or <b>M<sub>L</sub></b>.<sup id="cite_ref-11" class="reference"><a href="#cite_note-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup> Richter established two features now common to all magnitude scales. </p> <ol><li>First, the scale is logarithmic, so that each unit represents a ten-fold increase in the <i>amplitude</i> of the seismic waves.<sup id="cite_ref-12" class="reference"><a href="#cite_note-12"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup> As the energy of a wave is proportional to A<sup>1.5</sup>, where A denotes the amplitude, each unit of magnitude represents a 10<sup>1.5</sup>≈32-fold increase in the <i>seismic energy</i> (strength) of an earthquake.<sup id="cite_ref-13" class="reference"><a href="#cite_note-13"><span class="cite-bracket">[</span>13<span class="cite-bracket">]</span></a></sup></li> <li>Second, Richter arbitrarily defined the zero point of the scale to be where an earthquake at a distance of 100 km makes a maximum horizontal displacement of 0.001 millimeters (1 μm, or 0.00004 in.) on a seismogram recorded with a <a href="/wiki/Wood-Anderson_seismometer" class="mw-redirect" title="Wood-Anderson seismometer">Wood-Anderson torsion seismograph</a>.<sup id="cite_ref-14" class="reference"><a href="#cite_note-14"><span class="cite-bracket">[</span>14<span class="cite-bracket">]</span></a></sup> Subsequent magnitude scales are calibrated to be approximately in accord with the original "Richter" (local) scale around magnitude 6.<sup id="cite_ref-15" class="reference"><a href="#cite_note-15"><span class="cite-bracket">[</span>15<span class="cite-bracket">]</span></a></sup></li></ol> <p>All "Local" (ML) magnitudes are based on the maximum amplitude of the ground shaking, without distinguishing the different seismic waves. They underestimate the strength: </p> <ul><li>of <i>distant earthquakes</i> (over ~600 km) because of attenuation of the S waves,</li> <li>of <i>deep earthquakes</i> because the surface waves are smaller, and</li> <li>of <i>strong earthquakes</i> (over M ~7) because they do not take into account the duration of shaking.</li></ul> <p>The original "Richter" scale, developed in the geological context of Southern California and Nevada, was later found to be inaccurate for earthquakes in the central and eastern parts of the continent (everywhere east of the <a href="/wiki/Rocky_Mountains" title="Rocky Mountains">Rocky Mountains</a>) because of differences in the continental crust.<sup id="cite_ref-16" class="reference"><a href="#cite_note-16"><span class="cite-bracket">[</span>16<span class="cite-bracket">]</span></a></sup> All these problems prompted the development of other scales. </p><p>Most seismological authorities, such as the <a href="/wiki/United_States_Geological_Survey" title="United States Geological Survey">United States Geological Survey</a>, report earthquake magnitudes above 4.0 as <i>moment magnitude</i> (below), which the press describes as "Richter magnitude".<sup id="cite_ref-17" class="reference"><a href="#cite_note-17"><span class="cite-bracket">[</span>17<span class="cite-bracket">]</span></a></sup> </p><p><span class="anchor" id="Ml"></span> </p> <div class="mw-heading mw-heading3"><h3 id="Other_"local"_magnitude_scales"><span id="Other_.22local.22_magnitude_scales"></span>Other "local" magnitude scales</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Seismic_magnitude_scales&action=edit&section=4" title="Edit section: Other "local" magnitude scales"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Richter's original "local" scale has been adapted for other localities. These may be labelled "ML", or with a lowercase "<kbd>l</kbd>", either <b>M<kbd>l</kbd></b>, or <b>M<sub><kbd>l</kbd></sub></b>.<sup id="cite_ref-18" class="reference"><a href="#cite_note-18"><span class="cite-bracket">[</span>18<span class="cite-bracket">]</span></a></sup> (Not to be confused with the Russian surface-wave MLH scale.<sup id="cite_ref-19" class="reference"><a href="#cite_note-19"><span class="cite-bracket">[</span>19<span class="cite-bracket">]</span></a></sup>) Whether the values are comparable depends on whether the local conditions have been adequately determined and the formula suitably adjusted.<sup id="cite_ref-20" class="reference"><a href="#cite_note-20"><span class="cite-bracket">[</span>20<span class="cite-bracket">]</span></a></sup> </p><p><span class="anchor" id="Mjma"></span><span class="anchor" id="MJMA"></span> </p> <div class="mw-heading mw-heading4"><h4 id="Japan_Meteorological_Agency_magnitude_scale">Japan Meteorological Agency magnitude scale</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Seismic_magnitude_scales&action=edit&section=5" title="Edit section: Japan Meteorological Agency magnitude scale"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/Japan_Meteorological_Agency_magnitude_scale" title="Japan Meteorological Agency magnitude scale">Japan Meteorological Agency magnitude scale</a></div> <p>In Japan, for shallow (depth < 60 km) earthquakes within 600 km, the Japanese Meteorological Agency calculates<sup id="cite_ref-21" class="reference"><a href="#cite_note-21"><span class="cite-bracket">[</span>21<span class="cite-bracket">]</span></a></sup> a magnitude labeled <b>MJMA</b>, <b>M<sub>JMA</sub></b>, or <b>M<sub><kbd>J</kbd></sub></b>. (These should not be confused with moment magnitudes JMA calculates, which are labeled M<sub>w</sub>(JMA) or M<sup>(JMA)</sup>, nor with the <a href="/wiki/Japan_Meteorological_Agency_seismic_intensity_scale" title="Japan Meteorological Agency seismic intensity scale">Shindo intensity scale</a>.) JMA magnitudes are based (as typical with local scales) on the maximum amplitude of the <a href="/wiki/Ground_motion" title="Ground motion">ground motion</a>; they agree "rather well"<sup id="cite_ref-22" class="reference"><a href="#cite_note-22"><span class="cite-bracket">[</span>22<span class="cite-bracket">]</span></a></sup> with the seismic moment magnitude M<sub>w</sub>  in the range of 4.5 to 7.5,<sup id="cite_ref-23" class="reference"><a href="#cite_note-23"><span class="cite-bracket">[</span>23<span class="cite-bracket">]</span></a></sup> but underestimate larger magnitudes. </p><p><span class="anchor" id="mB"></span><span class="anchor" id="mb"></span><span class="anchor" id="mbLg"></span><span class="anchor" id="mN"></span> </p> <div class="mw-heading mw-heading3"><h3 id="Body-wave_magnitude_scales">Body-wave magnitude scales</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Seismic_magnitude_scales&action=edit&section=6" title="Edit section: Body-wave magnitude scales"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/Body_wave_magnitude" title="Body wave magnitude">Body wave magnitude</a></div> <p>Body-waves consist of <a href="/wiki/P_waves" class="mw-redirect" title="P waves">P waves</a> that are the first to arrive (see seismogram), or <a href="/wiki/S_waves" class="mw-redirect" title="S waves">S waves</a>, or reflections of either. Body-waves travel through rock directly.<sup id="cite_ref-24" class="reference"><a href="#cite_note-24"><span class="cite-bracket">[</span>24<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading4"><h4 id="mB_scale">mB scale</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Seismic_magnitude_scales&action=edit&section=7" title="Edit section: mB scale"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The original "body-wave magnitude" – <b>mB</b> or <b>m<sub>B</sub></b> (uppercase "B") – was developed by <a href="#CITEREFGutenberg1945c">Gutenberg 1945c</a> and <a href="#CITEREFGutenbergRichter1956">Gutenberg & Richter 1956</a><sup id="cite_ref-25" class="reference"><a href="#cite_note-25"><span class="cite-bracket">[</span>25<span class="cite-bracket">]</span></a></sup> to overcome the distance and magnitude limitations of the M<sub>L</sub>  scale inherent in the use of surface waves. mB  is based on the P and S waves, measured over a longer period, and does not saturate until around M 8. However, it is not sensitive to events smaller than about M 5.5.<sup id="cite_ref-26" class="reference"><a href="#cite_note-26"><span class="cite-bracket">[</span>26<span class="cite-bracket">]</span></a></sup> Use of mB  as originally defined has been largely abandoned,<sup id="cite_ref-27" class="reference"><a href="#cite_note-27"><span class="cite-bracket">[</span>27<span class="cite-bracket">]</span></a></sup> now replaced by the standardized <b>mB<sub>BB</sub> </b> scale.<sup id="cite_ref-28" class="reference"><a href="#cite_note-28"><span class="cite-bracket">[</span>28<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading4"><h4 id="mb_scale_2">mb scale</h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Seismic_magnitude_scales&action=edit&section=8" title="Edit section: mb scale"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The <b>mb</b> or <b>m<sub>b</sub></b> scale (lowercase "m" and "b") is similar to mB , but uses only P waves measured in the first few seconds on a specific model of short-period seismograph.<sup id="cite_ref-29" class="reference"><a href="#cite_note-29"><span class="cite-bracket">[</span>29<span class="cite-bracket">]</span></a></sup> It was introduced in the 1960s with the establishment of the <i><a href="/wiki/World-Wide_Standardized_Seismograph_Network" title="World-Wide Standardized Seismograph Network">World-Wide Standardized Seismograph Network</a></i> (WWSSN); the short period improves detection of smaller events, and better discriminates between tectonic earthquakes and underground nuclear explosions.<sup id="cite_ref-30" class="reference"><a href="#cite_note-30"><span class="cite-bracket">[</span>30<span class="cite-bracket">]</span></a></sup> </p><p>Measurement of mb  has changed several times.<sup id="cite_ref-31" class="reference"><a href="#cite_note-31"><span class="cite-bracket">[</span>31<span class="cite-bracket">]</span></a></sup> As originally defined by <a href="#CITEREFGutenberg1945c">Gutenberg (1945c)</a> m<sub>b</sub> was based on the maximum amplitude of waves in the first 10 seconds or more. However, the length of the period influences the magnitude obtained. Early USGS/NEIC practice was to measure mb  on the first second (just the first few P waves<sup id="cite_ref-32" class="reference"><a href="#cite_note-32"><span class="cite-bracket">[</span>32<span class="cite-bracket">]</span></a></sup>), but since 1978 they measure the first twenty seconds.<sup id="cite_ref-33" class="reference"><a href="#cite_note-33"><span class="cite-bracket">[</span>33<span class="cite-bracket">]</span></a></sup> The modern practice is to measure short-period mb  scale at less than three seconds, while the broadband <b>mB<sub>BB</sub> </b> scale is measured at periods of up to 30 seconds.<sup id="cite_ref-34" class="reference"><a href="#cite_note-34"><span class="cite-bracket">[</span>34<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading4"><h4 id="mbLg_scale">mb<sub>Lg</sub> scale <span class="anchor" id="Nuttli"></span></h4><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Seismic_magnitude_scales&action=edit&section=9" title="Edit section: mbLg scale"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:USGS-FS017-03_madrid.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/f/f2/USGS-FS017-03_madrid.jpg/400px-USGS-FS017-03_madrid.jpg" decoding="async" width="400" height="263" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/f/f2/USGS-FS017-03_madrid.jpg/600px-USGS-FS017-03_madrid.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/f/f2/USGS-FS017-03_madrid.jpg 2x" data-file-width="683" data-file-height="449" /></a><figcaption>Differences in the crust underlying North America east of the Rocky Mountains makes that area more sensitive to earthquakes. Shown here: the <a href="/wiki/1895_Charleston_earthquake" title="1895 Charleston earthquake">1895 New Madrid earthquake</a>, M ~6, was felt through most of the central U.S., while the 1994 <a href="/wiki/Northridge_quake" class="mw-redirect" title="Northridge quake">Northridge quake</a>, though almost ten times stronger at M 6.7, was felt only in southern California. From USGS Fact Sheet 017–03.</figcaption></figure> <p>The regional <b>mb<sub>Lg</sub></b> scale – also denoted <b>mb_Lg</b>, <b>mbLg</b>, <b>MLg</b> (USGS), <b>Mn</b>, and <b>m<sub>N</sub></b> – was developed by <a href="#CITEREFNuttli1973">Nuttli (1973)</a> for a problem the original M<sub>L</sub> scale could not handle: all of North America east of the <a href="/wiki/Rocky_Mountains" title="Rocky Mountains">Rocky Mountains</a>. The M<sub>L</sub> scale was developed in southern California, which lies on blocks of oceanic crust, typically <a href="/wiki/Basalt" title="Basalt">basalt</a> or sedimentary rock, which have been accreted to the continent. East of the Rockies the continent is a <a href="/wiki/Craton" title="Craton">craton</a>, a thick and largely stable mass of continental crust that is largely <a href="/wiki/Granite" title="Granite">granite</a>, a harder rock with different seismic characteristics. In this area the M<sub>L</sub> scale gives anomalous results for earthquakes which by other measures seemed equivalent to quakes in California. </p><p>Nuttli resolved this by measuring the amplitude of short-period (~1 sec.) Lg waves,<sup id="cite_ref-35" class="reference"><a href="#cite_note-35"><span class="cite-bracket">[</span>35<span class="cite-bracket">]</span></a></sup> a complex form of the <a href="/wiki/Love_wave" title="Love wave">Love wave</a> which, although a surface wave, he found provided a result more closely related to the mb  scale than the M<sub>s</sub>  scale.<sup id="cite_ref-36" class="reference"><a href="#cite_note-36"><span class="cite-bracket">[</span>36<span class="cite-bracket">]</span></a></sup> Lg waves attenuate quickly along any oceanic path, but propagate well through the granitic continental crust, and Mb<sub>Lg</sub> is often used in areas of stable continental crust; it is especially useful for detecting underground nuclear explosions.<sup id="cite_ref-37" class="reference"><a href="#cite_note-37"><span class="cite-bracket">[</span>37<span class="cite-bracket">]</span></a></sup> </p><p><span class="anchor" id="Ms"></span><span class="anchor" id="Ms20"></span><span class="anchor" id="Msbb"></span><span class="anchor" id="Msn"></span><span class="anchor" id="Ms7"></span><span class="anchor" id="MLH"></span> </p> <div class="mw-heading mw-heading3"><h3 id="Surface-wave_magnitude_scales">Surface-wave magnitude scales</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Seismic_magnitude_scales&action=edit&section=10" title="Edit section: Surface-wave magnitude scales"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/Surface-wave_magnitude" title="Surface-wave magnitude">Surface-wave magnitude</a></div> <p>Surface waves propagate along the Earth's surface, and are principally either <a href="/wiki/Rayleigh_wave" title="Rayleigh wave">Rayleigh waves</a> or <a href="/wiki/Love_wave" title="Love wave">Love waves</a>.<sup id="cite_ref-38" class="reference"><a href="#cite_note-38"><span class="cite-bracket">[</span>38<span class="cite-bracket">]</span></a></sup> For shallow earthquakes the surface waves carry most of the energy of the earthquake, and are the most destructive. Deeper earthquakes, having less interaction with the surface, produce weaker surface waves. </p><p>The surface-wave magnitude scale, variously denoted as <i>Ms</i>, <i>M<sub>S</sub></i>, and <i>M<sub>s</sub></i>, is based on a procedure developed by Beno Gutenberg in 1942<sup id="cite_ref-39" class="reference"><a href="#cite_note-39"><span class="cite-bracket">[</span>39<span class="cite-bracket">]</span></a></sup> for measuring shallow earthquakes stronger or more distant than Richter's original scale could handle. Notably, it measured the amplitude of surface waves (which generally produce the largest amplitudes) for a period of "about 20 seconds".<sup id="cite_ref-40" class="reference"><a href="#cite_note-40"><span class="cite-bracket">[</span>40<span class="cite-bracket">]</span></a></sup> The M<sub>s</sub>  scale approximately agrees with M<sub>L</sub>  at ~6, then diverges by as much as half a magnitude.<sup id="cite_ref-41" class="reference"><a href="#cite_note-41"><span class="cite-bracket">[</span>41<span class="cite-bracket">]</span></a></sup> A revision by <a href="#CITEREFNuttli1983">Nuttli (1983)</a>, sometimes labeled <i>M<sub>Sn</sub></i>,<sup id="cite_ref-42" class="reference"><a href="#cite_note-42"><span class="cite-bracket">[</span>42<span class="cite-bracket">]</span></a></sup> measures only waves of the first second. </p><p>A modification – the "Moscow-Prague formula" – was proposed in 1962, and recommended by the IASPEI in 1967; this is the basis of the standardized M<sub>s20</sub> scale (Ms_20, M<sub>s</sub>(20)).<sup id="cite_ref-43" class="reference"><a href="#cite_note-43"><span class="cite-bracket">[</span>43<span class="cite-bracket">]</span></a></sup> A "broad-band" variant (<i>Ms_BB</i>, <i>M<sub>s</sub>(BB)</i>) measures the largest velocity amplitude in the Rayleigh-wave train for periods up to 60 seconds.<sup id="cite_ref-44" class="reference"><a href="#cite_note-44"><span class="cite-bracket">[</span>44<span class="cite-bracket">]</span></a></sup> The M<sub>S7</sub> scale used in China is a variant of M<sub>s</sub> calibrated for use with the Chinese-made "type 763" long-period seismograph.<sup id="cite_ref-45" class="reference"><a href="#cite_note-45"><span class="cite-bracket">[</span>45<span class="cite-bracket">]</span></a></sup> </p><p>The MLH scale used in some parts of Russia is actually a surface-wave magnitude.<sup id="cite_ref-46" class="reference"><a href="#cite_note-46"><span class="cite-bracket">[</span>46<span class="cite-bracket">]</span></a></sup> </p><p><span class="anchor" id="M0"></span><span class="anchor" id="Mw"></span><span class="anchor" id="Mww"></span><span class="anchor" id="Mwb"></span><span class="anchor" id="Mwc"></span><span class="anchor" id="Mwp"></span><span class="anchor" id="Mwr"></span><span class="anchor" id="Mwpd"></span><span class="anchor" id="Mi"></span><span class="anchor" id="Mwbc"></span><span class="anchor" id="Me"></span> </p> <div class="mw-heading mw-heading3"><h3 id="Moment_magnitude_and_energy_magnitude_scales">Moment magnitude and energy magnitude scales</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Seismic_magnitude_scales&action=edit&section=11" title="Edit section: Moment magnitude and energy magnitude scales"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/Moment_magnitude_scale" title="Moment magnitude scale">Moment magnitude scale</a></div> <p>Other magnitude scales are based on aspects of seismic waves that only indirectly and incompletely reflect the force of an earthquake, involve other factors, and are generally limited in some respect of magnitude, focal depth, or distance. The <i>moment magnitude scale</i> – <i>Mw</i> or <i>M<sub>w</sub></i> – developed by seismologists <a href="/wiki/Thomas_C._Hanks" title="Thomas C. Hanks">Thomas C. Hanks</a> and <a href="/wiki/Hiroo_Kanamori" title="Hiroo Kanamori">Hiroo Kanamori</a>,<sup id="cite_ref-47" class="reference"><a href="#cite_note-47"><span class="cite-bracket">[</span>47<span class="cite-bracket">]</span></a></sup> is based on an earthquake's <i><a href="/wiki/Seismic_moment" title="Seismic moment">seismic moment</a></i>, <i>M<sub>0</sub></i>, a measure of how much <a href="/wiki/Work_(physics)" title="Work (physics)">work</a> an earthquake does in sliding one patch of rock past another patch of rock.<sup id="cite_ref-48" class="reference"><a href="#cite_note-48"><span class="cite-bracket">[</span>48<span class="cite-bracket">]</span></a></sup> Seismic moment is measured in <a href="/wiki/Newton-metre" title="Newton-metre">Newton-meters</a> (Nm or <span class="nowrap">N·m</span>) in the <a href="/wiki/SI_system" class="mw-redirect" title="SI system">SI system</a> of measurement, or <a href="/wiki/Dyne" title="Dyne">dyne-centimeters</a> (dyn-cm; <span class="nowrap">1 dyn-cm = 10<sup>−7</sup> Nm</span>) in the older <a href="/wiki/CGS" class="mw-redirect" title="CGS">CGS</a> system. In the simplest case the moment can be calculated knowing only the amount of slip, the area of the surface ruptured or slipped, and a factor for the resistance or friction encountered. These factors can be estimated for an existing fault to determine the magnitude of past earthquakes, or what might be anticipated for the future.<sup id="cite_ref-49" class="reference"><a href="#cite_note-49"><span class="cite-bracket">[</span>49<span class="cite-bracket">]</span></a></sup> </p><p>An earthquake's seismic moment can be estimated in various ways, which are the bases of the M<sub>wb</sub>, M<sub>wr</sub>, M<sub>wc</sub>, M<sub>ww</sub>, M<sub>wp</sub>, M<sub>i</sub>, and M<sub>wpd</sub> scales, all subtypes of the generic M<sub>w</sub> scale. See <a href="/wiki/Moment_magnitude_scale#Subtypes" title="Moment magnitude scale">Moment magnitude scale § Subtypes</a> for details. </p><p>Seismic moment is considered the most objective measure of an earthquake's "size" in regard of total energy.<sup id="cite_ref-50" class="reference"><a href="#cite_note-50"><span class="cite-bracket">[</span>50<span class="cite-bracket">]</span></a></sup> However, it is based on a simple model of rupture, and on certain simplifying assumptions; it does not account for the fact that the proportion of energy radiated as seismic waves varies among earthquakes.<sup id="cite_ref-51" class="reference"><a href="#cite_note-51"><span class="cite-bracket">[</span>51<span class="cite-bracket">]</span></a></sup> </p><p>Much of an earthquake's total energy as measured by M<sub>w</sub>  is dissipated as friction (resulting in heating of the crust).<sup id="cite_ref-52" class="reference"><a href="#cite_note-52"><span class="cite-bracket">[</span>52<span class="cite-bracket">]</span></a></sup> An earthquake's potential to cause strong ground shaking depends on the comparatively small fraction of energy radiated as seismic waves, and is better measured on the <i>energy magnitude</i> scale, <i>M<sub>e</sub></i>.<sup id="cite_ref-53" class="reference"><a href="#cite_note-53"><span class="cite-bracket">[</span>53<span class="cite-bracket">]</span></a></sup> The proportion of total energy radiated as seismic waves varies greatly depending on focal mechanism and tectonic environment;<sup id="cite_ref-54" class="reference"><a href="#cite_note-54"><span class="cite-bracket">[</span>54<span class="cite-bracket">]</span></a></sup> M<sub>e</sub>  and M<sub>w</sub>  for very similar earthquakes can differ by as much as 1.4 units.<sup id="cite_ref-55" class="reference"><a href="#cite_note-55"><span class="cite-bracket">[</span>55<span class="cite-bracket">]</span></a></sup> </p><p>Despite the usefulness of the M<sub>e</sub>  scale, it is not generally used due to difficulties in estimating the radiated seismic energy.<sup id="cite_ref-56" class="reference"><a href="#cite_note-56"><span class="cite-bracket">[</span>56<span class="cite-bracket">]</span></a></sup> </p> <p><span class="anchor" id="Two_quakes"></span></p><div style="border: 1px solid #005000;margin: 2em; padding: 1em;"> <style data-mw-deduplicate="TemplateStyles:r1239549316">.mw-parser-output .refbegin{margin-bottom:0.5em}.mw-parser-output .refbegin-hanging-indents>ul{margin-left:0}.mw-parser-output .refbegin-hanging-indents>ul>li{margin-left:0;padding-left:3.2em;text-indent:-3.2em}.mw-parser-output .refbegin-hanging-indents ul,.mw-parser-output .refbegin-hanging-indents ul li{list-style:none}@media(max-width:720px){.mw-parser-output .refbegin-hanging-indents>ul>li{padding-left:1.6em;text-indent:-1.6em}}.mw-parser-output .refbegin-columns{margin-top:0.3em}.mw-parser-output .refbegin-columns ul{margin-top:0}.mw-parser-output .refbegin-columns li{page-break-inside:avoid;break-inside:avoid-column}@media screen{.mw-parser-output .refbegin{font-size:90%}}</style><div class="refbegin" style=""> <p><b>Two earthquakes differing greatly in the damage done</b> </p><p>In 1997 there were two large earthquakes off the coast of Chile. The magnitude of the first, in July, was estimated at M<sub>w</sub> 6.9, but was barely felt, and only in three places. In October a M<sub>w</sub> 7.1 quake in nearly the same location, but twice as deep and on a different kind of fault, was felt over a broad area, injured over 300 people, and destroyed or seriously damaged over 10,000 houses. As can be seen in the table below, this disparity of damage done is not reflected in either the moment magnitude (M<sub>w</sub> ) nor the surface-wave magnitude (M<sub>s</sub> ). Only when the magnitude is measured on the basis of the body-wave (mb ) or the seismic energy (M<sub>e</sub> ) is there a difference comparable to the difference in damage. </p> <table class="wikitable"> <tbody><tr> <th>Date</th> <th><a href="/wiki/International_Seismological_Centre" title="International Seismological Centre">ISC</a> # </th> <th>Lat.</th> <th>Long.</th> <th>Depth</th> <th>Damage </th> <th>M<sub>s</sub> </th> <th>M<sub>w</sub> </th> <th>mb </th> <th>M<sub>e</sub>  </th> <th>Type of fault </th></tr> <tr> <td><span style="visibility:hidden;color:transparent;">0</span>6 July 1997</td> <td><a rel="nofollow" class="external text" href="http://www.isc.ac.uk/cgi-bin/FormatBibprint.pl?evid=1035633">1035633</a> </td> <td>−30.06</td> <td>−71.87</td> <td>23 km</td> <td>Barely felt </td> <td>6.5</td> <td>6.9</td> <td><b>5.8</b></td> <td><b>6.1</b> </td> <td>interplate-thrust </td></tr> <tr> <td>15 Oct. 1997</td> <td><a rel="nofollow" class="external text" href="http://www.isc.ac.uk/cgi-bin/FormatBibprint.pl?evid=1047434">1047434</a> </td> <td>−30.93</td> <td>−71.22</td> <td>58 km</td> <td>Extensive </td> <td>6.8</td> <td>7.1</td> <td><b>6.8</b></td> <td><b>7.5</b> </td> <td>intraslab-normal </td></tr> <tr> <td>Difference: </td> <td colspan="5"> </td> <td>0.3</td> <td>0.2</td> <td><b>1.0</b></td> <td><b>1.4</b> </td></tr></tbody></table> <p>Rearranged and adapted from Table 1 in <a href="#CITEREFChoyBoatwrightKirby2001">Choy, Boatwright & Kirby 2001</a>, p. 13. Seen also in <a href="#CITEREFIS_3.62012">IS 3.6 2012</a>, p. 7. </p> </div> </div> <p><span class="anchor" id="K"></span><span class="anchor" id="Mk"></span><span class="anchor" id="MK"></span> </p> <div class="mw-heading mw-heading3"><h3 id="Energy_class_(K-class)_scale"><span id="Energy_class_.28K-class.29_scale"></span>Energy class (<i>K</i>-class) scale</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Seismic_magnitude_scales&action=edit&section=12" title="Edit section: Energy class (K-class) scale"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/Energy_class" title="Energy class">Energy class</a></div> <p><i>K</i> (from the Russian word класс, 'class', in the sense of a category<sup id="cite_ref-57" class="reference"><a href="#cite_note-57"><span class="cite-bracket">[</span>57<span class="cite-bracket">]</span></a></sup>) is a measure of earthquake magnitude in the <i>energy class</i> or <i>K-class</i> system, developed in 1955 by <a href="/wiki/Soviet_Union" title="Soviet Union">Soviet</a> seismologists in the remote Garm (<a href="/wiki/Tajikistan" title="Tajikistan">Tajikistan</a>) region of Central Asia; in revised form it is still used for local and regional quakes in many states formerly aligned with the Soviet Union (including Cuba). Based on seismic energy (K = log E<sub>S</sub>, in <a href="/wiki/Joules" class="mw-redirect" title="Joules">Joules</a>), difficulty in implementing it using the technology of the time led to revisions in 1958 and 1960. Adaptation to local conditions has led to various regional K scales, such as <i>K<sub>F</sub></i> and <i>K<sub>S</sub></i>.<sup id="cite_ref-58" class="reference"><a href="#cite_note-58"><span class="cite-bracket">[</span>58<span class="cite-bracket">]</span></a></sup> </p><p>K values are logarithmic, similar to Richter-style magnitudes, but have a different scaling and zero point. K values in the range of 12 to 15 correspond approximately to M 4.5 to 6.<sup id="cite_ref-59" class="reference"><a href="#cite_note-59"><span class="cite-bracket">[</span>59<span class="cite-bracket">]</span></a></sup> M(K), M<sub>(K)</sub>, or possibly M<sub>K</sub> indicates a magnitude M calculated from an energy class K.<sup id="cite_ref-60" class="reference"><a href="#cite_note-60"><span class="cite-bracket">[</span>60<span class="cite-bracket">]</span></a></sup> </p><p><span class="anchor" id="Mt"></span><span class="anchor" id="Mm"></span> </p> <div class="mw-heading mw-heading3"><h3 id="Tsunami_magnitude_scales">Tsunami magnitude scales</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Seismic_magnitude_scales&action=edit&section=13" title="Edit section: Tsunami magnitude scales"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Earthquakes that generate tsunamis generally rupture relatively slowly, delivering more energy at longer periods (lower frequencies) than generally used for measuring magnitudes. Any skew in the spectral distribution can result in larger, or smaller, tsunamis than expected for a nominal magnitude.<sup id="cite_ref-61" class="reference"><a href="#cite_note-61"><span class="cite-bracket">[</span>61<span class="cite-bracket">]</span></a></sup> The tsunami magnitude scale, <i>M<sub>t</sub></i>, is based on a correlation by Katsuyuki Abe of earthquake seismic moment (M<sub><small>0</small></sub> ) with the amplitude of tsunami waves as measured by tidal gauges.<sup id="cite_ref-62" class="reference"><a href="#cite_note-62"><span class="cite-bracket">[</span>62<span class="cite-bracket">]</span></a></sup> Originally intended for estimating the magnitude of historic earthquakes where seismic data is lacking but tidal data exist, the correlation can be reversed to predict tidal height from earthquake magnitude.<sup id="cite_ref-63" class="reference"><a href="#cite_note-63"><span class="cite-bracket">[</span>63<span class="cite-bracket">]</span></a></sup> (Not to be confused with the height of a tidal wave, or <i>run-up</i>, which is an intensity effect controlled by local topography.) Under low-noise conditions, tsunami waves as little as 5 cm can be predicted, corresponding to an earthquake of M ~6.5.<sup id="cite_ref-64" class="reference"><a href="#cite_note-64"><span class="cite-bracket">[</span>64<span class="cite-bracket">]</span></a></sup> </p><p>Another scale of particular importance for tsunami warnings is the mantle magnitude scale, <i>M<sub>m</sub></i>.<sup id="cite_ref-65" class="reference"><a href="#cite_note-65"><span class="cite-bracket">[</span>65<span class="cite-bracket">]</span></a></sup> This is based on Rayleigh waves that penetrate into the Earth's mantle, and can be determined quickly, and without complete knowledge of other parameters such as the earthquake's depth. </p><p><span class="anchor" id="Md"></span><span class="anchor" id="Mc"></span> </p> <div class="mw-heading mw-heading3"><h3 id="Duration_and_coda_magnitude_scales">Duration and coda magnitude scales</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Seismic_magnitude_scales&action=edit&section=14" title="Edit section: Duration and coda magnitude scales"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/Earthquake_duration_magnitude" title="Earthquake duration magnitude">Earthquake duration magnitude</a></div> <p><i>M<sub>d</sub></i> designates various scales that estimate magnitude from the <i>duration</i> or length of some part of the seismic wave-train. This is especially useful for measuring local or regional earthquakes, both powerful earthquakes that might drive the seismometer off-scale (a problem with the analog instruments formerly used) and preventing measurement of the maximum wave amplitude, and weak earthquakes, whose maximum amplitude is not accurately measured. Even for distant earthquakes, measuring the duration of the shaking (as well as the amplitude) provides a better measure of the earthquake's total energy. Measurement of duration is incorporated in some modern scales, such as M<sub>wpd</sub>  and mB<sub>c</sub> .<sup id="cite_ref-66" class="reference"><a href="#cite_note-66"><span class="cite-bracket">[</span>66<span class="cite-bracket">]</span></a></sup> </p><p>M<sub>c</sub> scales usually measure the duration or amplitude of a part of the seismic wave, the <i>coda</i>.<sup id="cite_ref-67" class="reference"><a href="#cite_note-67"><span class="cite-bracket">[</span>67<span class="cite-bracket">]</span></a></sup> For short distances (less than ~100 km) these can provide a quick estimate of magnitude before the quake's exact location is known.<sup id="cite_ref-68" class="reference"><a href="#cite_note-68"><span class="cite-bracket">[</span>68<span class="cite-bracket">]</span></a></sup> </p><p><span class="anchor" id="Mms"></span><span class="anchor" id="Mfa"></span><span class="anchor" id="Mla"></span><span class="anchor" id="MI"></span> </p> <div class="mw-heading mw-heading3"><h3 id="Macroseismic_magnitude_scales">Macroseismic magnitude scales</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Seismic_magnitude_scales&action=edit&section=15" title="Edit section: Macroseismic magnitude scales"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Magnitude scales generally are based on instrumental measurement of some aspect of the seismic wave as recorded on a seismogram. Where such records do not exist, magnitudes can be estimated from reports of the macroseismic events such as described by intensity scales.<sup id="cite_ref-69" class="reference"><a href="#cite_note-69"><span class="cite-bracket">[</span>69<span class="cite-bracket">]</span></a></sup> </p><p>One approach for doing this (developed by <a href="/wiki/Beno_Gutenberg" title="Beno Gutenberg">Beno Gutenberg</a> and Charles Richter in 1942<sup id="cite_ref-70" class="reference"><a href="#cite_note-70"><span class="cite-bracket">[</span>70<span class="cite-bracket">]</span></a></sup>) relates the maximum intensity observed (presumably this is over the epicenter), denoted <i>I<sub>0</sub></i> (capital I with a subscripted zero), to the magnitude. It has been recommended that magnitudes calculated on this basis be labeled <i>M<sub>w</sub>(I<sub>0</sub>)</i>,<sup id="cite_ref-71" class="reference"><a href="#cite_note-71"><span class="cite-bracket">[</span>71<span class="cite-bracket">]</span></a></sup> but are sometimes labeled with a more generic M<sub>ms</sub>. </p><p>Another approach is to make an <i><a href="/wiki/Isoseismal_map" title="Isoseismal map">isoseismal map</a></i> showing the area over which a given level of intensity was felt. The size of the "felt area" can also be related to the magnitude (based on the work of <a href="#CITEREFFrankel1994">Frankel 1994</a> and <a href="#CITEREFJohnston1996">Johnston 1996</a>). While the recommended label for magnitudes derived in this way is <i>M<sub>0</sub>(An)</i>,<sup id="cite_ref-72" class="reference"><a href="#cite_note-72"><span class="cite-bracket">[</span>72<span class="cite-bracket">]</span></a></sup> the more commonly seen label is <i>M<sub>fa</sub></i>.<sup id="cite_ref-73" class="reference"><a href="#cite_note-73"><span class="cite-bracket">[</span>73<span class="cite-bracket">]</span></a></sup> A variant, <i>M<sub>La</sub></i>, adapted to California and Hawaii, derives the local magnitude (M<sub>L</sub>) from the size of the area affected by a given intensity.<sup id="cite_ref-74" class="reference"><a href="#cite_note-74"><span class="cite-bracket">[</span>74<span class="cite-bracket">]</span></a></sup> M<sub><kbd>I</kbd></sub> (upper-case letter "<kbd>I</kbd>", distinguished from the lower-case letter in M<sub><kbd>i</kbd></sub>) has been used for moment magnitudes estimated from <i>isoseismal intensities</i> calculated per <a href="#CITEREFJohnston1996">Johnston 1996</a>.<sup id="cite_ref-75" class="reference"><a href="#cite_note-75"><span class="cite-bracket">[</span>75<span class="cite-bracket">]</span></a></sup> </p><p><i><a href="/wiki/Peak_ground_velocity" class="mw-redirect" title="Peak ground velocity">Peak ground velocity</a></i> (PGV) and <i><a href="/wiki/Peak_ground_acceleration" title="Peak ground acceleration">peak ground acceleration</a></i> (PGA) are measures of the force that causes destructive ground shaking.<sup id="cite_ref-76" class="reference"><a href="#cite_note-76"><span class="cite-bracket">[</span>76<span class="cite-bracket">]</span></a></sup> In Japan, a network of strong-motion accelerometers provides PGA data that permits site-specific correlation with different magnitude earthquakes. This correlation can be inverted to estimate the ground shaking at that site due to an earthquake of a given magnitude at a given distance. From this a map showing areas of likely damage can be prepared within minutes of an actual earthquake.<sup id="cite_ref-77" class="reference"><a href="#cite_note-77"><span class="cite-bracket">[</span>77<span class="cite-bracket">]</span></a></sup> </p><p><span class="anchor" id="UK"></span><span class="anchor" id="Muk"></span><span class="anchor" id="Mgr"></span><span class="anchor" id="Mh"></span> </p> <div class="mw-heading mw-heading3"><h3 id="Other_magnitude_scales">Other magnitude scales</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Seismic_magnitude_scales&action=edit&section=16" title="Edit section: Other magnitude scales"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Many earthquake magnitude scales have been developed or proposed, with some never gaining broad acceptance and remaining only as obscure references in historical catalogs of earthquakes. Other scales have been used without a definite name, often referred to as "the method of Smith (1965)" (or similar language), with the authors often revising their method. On top of this, seismological networks vary on how they measure seismograms. Where the details of how a magnitude has been determined are unknown, catalogs will specify the scale as "unknown" (variously <i>Unk</i>, <i>Ukn</i>, or <i>UK</i>). In such cases, the magnitude is considered generic and approximate. </p><p>An <i>M<sub>h</sub></i> ("magnitude determined by hand") label has been used where the magnitude is too small or the data too poor (typically from analog equipment) to determine a Local magnitude, or multiple shocks or cultural noise complicates the records. The <a href="/wiki/Southern_California_Seismic_Network" title="Southern California Seismic Network">Southern California Seismic Network</a> uses this "magnitude" where the data fail the quality criteria.<sup id="cite_ref-78" class="reference"><a href="#cite_note-78"><span class="cite-bracket">[</span>78<span class="cite-bracket">]</span></a></sup> </p><p>A special case is the <i>Seismicity of the Earth</i> catalog of <a href="#CITEREFGutenbergRichter1954">Gutenberg & Richter (1954)</a>. Hailed as a milestone as a comprehensive global catalog of earthquakes with uniformly calculated magnitudes,<sup id="cite_ref-79" class="reference"><a href="#cite_note-79"><span class="cite-bracket">[</span>79<span class="cite-bracket">]</span></a></sup> they never published the full details of how they determined those magnitudes.<sup id="cite_ref-80" class="reference"><a href="#cite_note-80"><span class="cite-bracket">[</span>80<span class="cite-bracket">]</span></a></sup> Consequently, while some catalogs identify these magnitudes as <i>M<sub>GR</sub></i>, others use <i>UK</i> (meaning "computational method unknown").<sup id="cite_ref-81" class="reference"><a href="#cite_note-81"><span class="cite-bracket">[</span>81<span class="cite-bracket">]</span></a></sup> Subsequent study found many of the M<sub>s</sub>  values to be "considerably overestimated".<sup id="cite_ref-82" class="reference"><a href="#cite_note-82"><span class="cite-bracket">[</span>82<span class="cite-bracket">]</span></a></sup> Further study has found that most of the M<sub>GR</sub>  magnitudes "are basically M<sub>s</sub>  for large shocks shallower than 40 km, but are basically mB  for large shocks at depths of 40–60 km."<sup id="cite_ref-83" class="reference"><a href="#cite_note-83"><span class="cite-bracket">[</span>83<span class="cite-bracket">]</span></a></sup> Gutenberg and Richter also used an italic, non-bold <i>M</i> without subscript<sup id="cite_ref-84" class="reference"><a href="#cite_note-84"><span class="cite-bracket">[</span>84<span class="cite-bracket">]</span></a></sup> – also used as a generic magnitude, and not to be confused with the bold, non-italic <b>M</b> used for <i>moment magnitude</i> – and a "unified magnitude" <i><b>m</b></i> (bolding added).<sup id="cite_ref-85" class="reference"><a href="#cite_note-85"><span class="cite-bracket">[</span>85<span class="cite-bracket">]</span></a></sup> While these terms (with various adjustments) were used in scientific articles into the 1970s,<sup id="cite_ref-86" class="reference"><a href="#cite_note-86"><span class="cite-bracket">[</span>86<span class="cite-bracket">]</span></a></sup> they are now only of historical interest. An ordinary (non-italic, non-bold) capital "M" without subscript is often used to refer to magnitude generically, where an exact value or the specific scale used is not important. </p> <div class="mw-heading mw-heading2"><h2 id="See_also">See also</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Seismic_magnitude_scales&action=edit&section=17" title="Edit section: See also"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a href="/wiki/Magnitude_of_completeness" title="Magnitude of completeness">Magnitude of completeness</a></li> <li><a href="/wiki/Epicentral_distance" title="Epicentral distance">Epicentral distance</a></li></ul> <div class="mw-heading mw-heading2"><h2 id="Citations">Citations</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Seismic_magnitude_scales&action=edit&section=18" title="Edit section: Citations"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1239543626">.mw-parser-output .reflist{margin-bottom:0.5em;list-style-type:decimal}@media screen{.mw-parser-output .reflist{font-size:90%}}.mw-parser-output .reflist .references{font-size:100%;margin-bottom:0;list-style-type:inherit}.mw-parser-output .reflist-columns-2{column-width:30em}.mw-parser-output .reflist-columns-3{column-width:25em}.mw-parser-output .reflist-columns{margin-top:0.3em}.mw-parser-output .reflist-columns ol{margin-top:0}.mw-parser-output .reflist-columns li{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .reflist-upper-alpha{list-style-type:upper-alpha}.mw-parser-output .reflist-upper-roman{list-style-type:upper-roman}.mw-parser-output .reflist-lower-alpha{list-style-type:lower-alpha}.mw-parser-output .reflist-lower-greek{list-style-type:lower-greek}.mw-parser-output .reflist-lower-roman{list-style-type:lower-roman}</style><div class="reflist"> <div class="mw-references-wrap mw-references-columns"><ol class="references"> <li id="cite_note-1"><span class="mw-cite-backlink"><b><a href="#cite_ref-1">^</a></b></span> <span class="reference-text"><a href="#CITEREFBormannWendtDi_Giacomo2013">Bormann, Wendt & Di Giacomo 2013</a>, p. 37. The relationship between magnitude and the energy released is complicated. See §3.1.2.5 and §3.3.3 for details.</span> </li> <li id="cite_note-2"><span class="mw-cite-backlink"><b><a href="#cite_ref-2">^</a></b></span> <span class="reference-text"><a href="#CITEREFBormannWendtDi_Giacomo2013">Bormann, Wendt & Di Giacomo 2013</a>, §3.1.2.1.</span> </li> <li id="cite_note-3"><span class="mw-cite-backlink"><b><a href="#cite_ref-3">^</a></b></span> <span class="reference-text"><a href="#CITEREFBolt1993">Bolt 1993</a>, p. 164 et seq..</span> </li> <li id="cite_note-4"><span class="mw-cite-backlink"><b><a href="#cite_ref-4">^</a></b></span> <span class="reference-text"><a href="#CITEREFBolt1993">Bolt 1993</a>, pp. 170–171.</span> </li> <li id="cite_note-5"><span class="mw-cite-backlink"><b><a href="#cite_ref-5">^</a></b></span> <span class="reference-text"><a href="#CITEREFBolt1993">Bolt 1993</a>, p. 170.</span> </li> <li id="cite_note-6"><span class="mw-cite-backlink"><b><a href="#cite_ref-6">^</a></b></span> <span class="reference-text">See <a href="#CITEREFBolt1993">Bolt 1993</a>, Chapters 2 and 3, for a very readable explanation of these waves and their interpretation. J. R. Kayal's description of seismic waves can be found <a rel="nofollow" class="external text" href="https://escweb.wr.usgs.gov/share/mooney/SriL.II2.pdf">here</a>.</span> </li> <li id="cite_note-7"><span class="mw-cite-backlink"><b><a href="#cite_ref-7">^</a></b></span> <span class="reference-text">See <a href="#CITEREFHavskovOttemöller2009">Havskov & Ottemöller 2009</a>, §1.4, pp. 20–21, for a short explanation, or MNSOP-2 <a href="#CITEREFEX_3.12012">EX 3.1 2012</a> for a technical description.</span> </li> <li id="cite_note-8"><span class="mw-cite-backlink"><b><a href="#cite_ref-8">^</a></b></span> <span class="reference-text"><a href="#CITEREFChungBernreuter1980">Chung & Bernreuter 1980</a>, p. 1.</span> </li> <li id="cite_note-9"><span class="mw-cite-backlink"><b><a href="#cite_ref-9">^</a></b></span> <span class="reference-text"><a href="#CITEREFBormannWendtDi_Giacomo2013">Bormann, Wendt & Di Giacomo 2013</a>, p. 18.</span> </li> <li id="cite_note-10"><span class="mw-cite-backlink"><b><a href="#cite_ref-10">^</a></b></span> <span class="reference-text">IASPEI <a href="#CITEREFIS_3.32014">IS 3.3 2014</a>, pp. 2–3.</span> </li> <li id="cite_note-11"><span class="mw-cite-backlink"><b><a href="#cite_ref-11">^</a></b></span> <span class="reference-text"><a href="#CITEREFKanamori1983">Kanamori 1983</a>, p. 187.</span> </li> <li id="cite_note-12"><span class="mw-cite-backlink"><b><a href="#cite_ref-12">^</a></b></span> <span class="reference-text"><a href="#CITEREFRichter1935">Richter 1935</a>, p. 7.</span> </li> <li id="cite_note-13"><span class="mw-cite-backlink"><b><a href="#cite_ref-13">^</a></b></span> <span class="reference-text"><a href="#CITEREFSpenceSipkinChoy1989">Spence, Sipkin & Choy 1989</a>, p. 61.</span> </li> <li id="cite_note-14"><span class="mw-cite-backlink"><b><a href="#cite_ref-14">^</a></b></span> <span class="reference-text"><a href="#CITEREFRichter1935">Richter 1935</a>, pp. 5; <a href="#CITEREFChungBernreuter1980">Chung & Bernreuter 1980</a>, p. 10. Subsequently redefined by <a href="#CITEREFHuttonBoore1987">Hutton & Boore 1987</a> as 10 mm of motion by an M<sub>L</sub> 3 quake at 17 km.</span> </li> <li id="cite_note-15"><span class="mw-cite-backlink"><b><a href="#cite_ref-15">^</a></b></span> <span class="reference-text"><a href="#CITEREFChungBernreuter1980">Chung & Bernreuter 1980</a>, p. 1; <a href="#CITEREFKanamori1983">Kanamori 1983</a>, p. 187, figure 2.</span> </li> <li id="cite_note-16"><span class="mw-cite-backlink"><b><a href="#cite_ref-16">^</a></b></span> <span class="reference-text"><a href="#CITEREFChungBernreuter1980">Chung & Bernreuter 1980</a>, p. ix.</span> </li> <li id="cite_note-17"><span class="mw-cite-backlink"><b><a href="#cite_ref-17">^</a></b></span> <span class="reference-text">The "USGS Earthquake Magnitude Policy" for reporting earthquake magnitudes to the public as formulated by the <i>USGS Earthquake Magnitude Working Group</i> was implemented January 18, 2002, and posted at <a rel="nofollow" class="external free" href="https://earthquake.usgs.gov/aboutus/docs/020204mag_policy.php">https://earthquake.usgs.gov/aboutus/docs/020204mag_policy.php</a>. It has since been removed; a copy is archived at the <a rel="nofollow" class="external text" href="https://web.archive.org/web/20160428095841/http://earthquake.usgs.gov:80/aboutus/docs/020204mag_policy.php">Wayback Machine</a>, and the essential part can be found <a rel="nofollow" class="external text" href="http://dapgeol.tripod.com/usgsearthquakemagnitudepolicy.htm">here</a>.</span> </li> <li id="cite_note-18"><span class="mw-cite-backlink"><b><a href="#cite_ref-18">^</a></b></span> <span class="reference-text"><a href="#CITEREFBormannWendtDi_Giacomo2013">Bormann, Wendt & Di Giacomo 2013</a>, §3.2.4, p. 59.</span> </li> <li id="cite_note-19"><span class="mw-cite-backlink"><b><a href="#cite_ref-19">^</a></b></span> <span class="reference-text"><a href="#CITEREFRautianLeith2002">Rautian & Leith 2002</a>, pp. 158, 162.</span> </li> <li id="cite_note-20"><span class="mw-cite-backlink"><b><a href="#cite_ref-20">^</a></b></span> <span class="reference-text">See Datasheet 3.1 in <a rel="nofollow" class="external text" href="http://bib.telegrafenberg.de/publizieren/vertrieb/nmsop/">NMSOP-2</a> <a rel="nofollow" class="external text" href="https://web.archive.org/web/20190804200233/http://bib.telegrafenberg.de/publizieren/vertrieb/nmsop/">Archived</a> 2019-08-04 at the <a href="/wiki/Wayback_Machine" title="Wayback Machine">Wayback Machine</a> for a partial compilation and references.</span> </li> <li id="cite_note-21"><span class="mw-cite-backlink"><b><a href="#cite_ref-21">^</a></b></span> <span class="reference-text"><a href="#CITEREFKatsumata1996">Katsumata 1996</a>; <a href="#CITEREFBormannWendtDi_Giacomo2013">Bormann, Wendt & Di Giacomo 2013</a>, §3.2.4.7, p. 78; <a href="#CITEREFDoi2010">Doi 2010</a>.</span> </li> <li id="cite_note-22"><span class="mw-cite-backlink"><b><a href="#cite_ref-22">^</a></b></span> <span class="reference-text"><a href="#CITEREFBormannSaul2009">Bormann & Saul 2009</a>, p. 2478.</span> </li> <li id="cite_note-23"><span class="mw-cite-backlink"><b><a href="#cite_ref-23">^</a></b></span> <span class="reference-text">See also figure 3.70 in NMSOP-2.</span> </li> <li id="cite_note-24"><span class="mw-cite-backlink"><b><a href="#cite_ref-24">^</a></b></span> <span class="reference-text"><a href="#CITEREFHavskovOttemöller2009">Havskov & Ottemöller 2009</a>, p. 17.</span> </li> <li id="cite_note-25"><span class="mw-cite-backlink"><b><a href="#cite_ref-25">^</a></b></span> <span class="reference-text"><a href="#CITEREFBormannWendtDi_Giacomo2013">Bormann, Wendt & Di Giacomo 2013</a>, p. 37; <a href="#CITEREFHavskovOttemöller2009">Havskov & Ottemöller 2009</a>, §6.5. See also <a href="#CITEREFAbe1981">Abe 1981</a>.</span> </li> <li id="cite_note-26"><span class="mw-cite-backlink"><b><a href="#cite_ref-26">^</a></b></span> <span class="reference-text"><a href="#CITEREFHavskovOttemöller2009">Havskov & Ottemöller 2009</a>, p. 191.</span> </li> <li id="cite_note-27"><span class="mw-cite-backlink"><b><a href="#cite_ref-27">^</a></b></span> <span class="reference-text"><a href="#CITEREFBormannSaul2009">Bormann & Saul 2009</a>, p. 2482.</span> </li> <li id="cite_note-28"><span class="mw-cite-backlink"><b><a href="#cite_ref-28">^</a></b></span> <span class="reference-text">MNSOP-2/IASPEI <a href="#CITEREFIS_3.32014">IS 3.3 2014</a>, §4.2, pp. 15–16.</span> </li> <li id="cite_note-29"><span class="mw-cite-backlink"><b><a href="#cite_ref-29">^</a></b></span> <span class="reference-text"><a href="#CITEREFKanamori1983">Kanamori 1983</a>, pp. 189, 196; <a href="#CITEREFChungBernreuter1980">Chung & Bernreuter 1980</a>, p. 5.</span> </li> <li id="cite_note-30"><span class="mw-cite-backlink"><b><a href="#cite_ref-30">^</a></b></span> <span class="reference-text"><a href="#CITEREFBormannWendtDi_Giacomo2013">Bormann, Wendt & Di Giacomo 2013</a>, pp. 37, 39; <a href="#CITEREFBolt1993">Bolt (1993</a>, pp. 88–93) examines this at length.</span> </li> <li id="cite_note-31"><span class="mw-cite-backlink"><b><a href="#cite_ref-31">^</a></b></span> <span class="reference-text"><a href="#CITEREFBormannWendtDi_Giacomo2013">Bormann, Wendt & Di Giacomo 2013</a>, p. 103.</span> </li> <li id="cite_note-32"><span class="mw-cite-backlink"><b><a href="#cite_ref-32">^</a></b></span> <span class="reference-text">IASPEI <a href="#CITEREFIS_3.32014">IS 3.3 2014</a>, p. 18.</span> </li> <li id="cite_note-33"><span class="mw-cite-backlink"><b><a href="#cite_ref-33">^</a></b></span> <span class="reference-text"><a href="#CITEREFNuttli1983">Nuttli 1983</a>, p. 104; <a href="#CITEREFBormannWendtDi_Giacomo2013">Bormann, Wendt & Di Giacomo 2013</a>, p. 103.</span> </li> <li id="cite_note-34"><span class="mw-cite-backlink"><b><a href="#cite_ref-34">^</a></b></span> <span class="reference-text">IASPEI/NMSOP-2 <a href="#CITEREFIS_3.22013">IS 3.2 2013</a>, p. 8.</span> </li> <li id="cite_note-35"><span class="mw-cite-backlink"><b><a href="#cite_ref-35">^</a></b></span> <span class="reference-text"><a href="#CITEREFBormannWendtDi_Giacomo2013">Bormann, Wendt & Di Giacomo 2013</a>, §3.2.4.4. The "g" subscript refers to the granitic layer through which L<sub>g</sub> waves propagate.<a href="#CITEREFChenPomeroy1980">Chen & Pomeroy 1980</a>, p. 4. See also J. R. Kayal, "Seismic Waves and Earthquake Location", <a rel="nofollow" class="external text" href="https://escweb.wr.usgs.gov/share/mooney/SriL.II2.pdf">here</a>, page 5.</span> </li> <li id="cite_note-36"><span class="mw-cite-backlink"><b><a href="#cite_ref-36">^</a></b></span> <span class="reference-text"><a href="#CITEREFNuttli1973">Nuttli 1973</a>, p. 881.</span> </li> <li id="cite_note-37"><span class="mw-cite-backlink"><b><a href="#cite_ref-37">^</a></b></span> <span class="reference-text"><a href="#CITEREFBormannWendtDi_Giacomo2013">Bormann, Wendt & Di Giacomo 2013</a>, §3.2.4.4.</span> </li> <li id="cite_note-38"><span class="mw-cite-backlink"><b><a href="#cite_ref-38">^</a></b></span> <span class="reference-text"><a href="#CITEREFHavskovOttemöller2009">Havskov & Ottemöller 2009</a>, pp. 17–19. See especially figure 1-10.</span> </li> <li id="cite_note-39"><span class="mw-cite-backlink"><b><a href="#cite_ref-39">^</a></b></span> <span class="reference-text"><a href="#CITEREFGutenberg1945a">Gutenberg 1945a</a>; based on work by <a href="#CITEREFGutenbergRichter1936">Gutenberg & Richter 1936</a>.</span> </li> <li id="cite_note-40"><span class="mw-cite-backlink"><b><a href="#cite_ref-40">^</a></b></span> <span class="reference-text"><a href="#CITEREFGutenberg1945a">Gutenberg 1945a</a>.</span> </li> <li id="cite_note-41"><span class="mw-cite-backlink"><b><a href="#cite_ref-41">^</a></b></span> <span class="reference-text"><a href="#CITEREFKanamori1983">Kanamori 1983</a>, p. 187.</span> </li> <li id="cite_note-42"><span class="mw-cite-backlink"><b><a href="#cite_ref-42">^</a></b></span> <span class="reference-text"><a href="#CITEREFStoverCoffman1993">Stover & Coffman 1993</a>, p. 3.</span> </li> <li id="cite_note-43"><span class="mw-cite-backlink"><b><a href="#cite_ref-43">^</a></b></span> <span class="reference-text"><a href="#CITEREFBormannWendtDi_Giacomo2013">Bormann, Wendt & Di Giacomo 2013</a>, pp. 81–84.</span> </li> <li id="cite_note-44"><span class="mw-cite-backlink"><b><a href="#cite_ref-44">^</a></b></span> <span class="reference-text">MNSOP-2 <a href="#CITEREFDS_3.12012">DS 3.1 2012</a>, p. 8.</span> </li> <li id="cite_note-45"><span class="mw-cite-backlink"><b><a href="#cite_ref-45">^</a></b></span> <span class="reference-text"><a href="#CITEREFBormannLiuRenGutdeutsch2007">Bormann et al. 2007</a>, p. 118.</span> </li> <li id="cite_note-46"><span class="mw-cite-backlink"><b><a href="#cite_ref-46">^</a></b></span> <span class="reference-text"><a href="#CITEREFRautianLeith2002">Rautian & Leith 2002</a>, pp. 162, 164.</span> </li> <li id="cite_note-47"><span class="mw-cite-backlink"><b><a href="#cite_ref-47">^</a></b></span> <span class="reference-text"><style data-mw-deduplicate="TemplateStyles:r1238218222">.mw-parser-output cite.citation{font-style:inherit;word-wrap:break-word}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}.mw-parser-output .id-lock-free.id-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/6/65/Lock-green.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-limited.id-lock-limited a,.mw-parser-output .id-lock-registration.id-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/d/d6/Lock-gray-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-subscription.id-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/a/aa/Lock-red-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .cs1-ws-icon a{background:url("//upload.wikimedia.org/wikipedia/commons/4/4c/Wikisource-logo.svg")right 0.1em center/12px no-repeat}body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-free a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-limited a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-registration a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-subscription a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .cs1-ws-icon a{background-size:contain;padding:0 1em 0 0}.mw-parser-output .cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:var(--color-error,#d33)}.mw-parser-output .cs1-visible-error{color:var(--color-error,#d33)}.mw-parser-output .cs1-maint{display:none;color:#085;margin-left:0.3em}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}@media screen{.mw-parser-output .cs1-format{font-size:95%}html.skin-theme-clientpref-night .mw-parser-output .cs1-maint{color:#18911f}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .cs1-maint{color:#18911f}}</style><cite id="CITEREFHanks1979" class="citation journal cs1">Hanks, Thomas (1979). <a rel="nofollow" class="external text" href="https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/JB084ib05p02348?casa_token=Ob3hlS8_Ur4AAAAA:V-crV2WsODI0_CZP662OUwD-t4uyd0-r3_RYD0dyHcjfF7S6OwvqVhY6GfdevVhtjmsqIERTz57y8cC7">"A moment magnitude scale"</a>. <i>Journal of Geophysical Research</i>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Journal+of+Geophysical+Research&rft.atitle=A+moment+magnitude+scale&rft.date=1979&rft.aulast=Hanks&rft.aufirst=Thomas&rft_id=https%3A%2F%2Fagupubs.onlinelibrary.wiley.com%2Fdoi%2Fabs%2F10.1029%2FJB084ib05p02348%3Fcasa_token%3DOb3hlS8_Ur4AAAAA%3AV-crV2WsODI0_CZP662OUwD-t4uyd0-r3_RYD0dyHcjfF7S6OwvqVhY6GfdevVhtjmsqIERTz57y8cC7&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASeismic+magnitude+scales" class="Z3988"></span></span> </li> <li id="cite_note-48"><span class="mw-cite-backlink"><b><a href="#cite_ref-48">^</a></b></span> <span class="reference-text">The IASPEI standard formula for deriving moment magnitude from seismic moment is<br /> M<sub>w</sub> <span class="nowrap"> </span>=<span class="nowrap"> </span>(2/3)<span class="nowrap"> </span>(log<span class="nowrap"> </span>M<sub><small>0</small></sub> <span class="nowrap"> </span>–<span class="nowrap"> </span>9.1). Formula 3.68 in <a href="#CITEREFBormannWendtDi_Giacomo2013">Bormann, Wendt & Di Giacomo 2013</a>, p. 125.</span> </li> <li id="cite_note-49"><span class="mw-cite-backlink"><b><a href="#cite_ref-49">^</a></b></span> <span class="reference-text"><a href="#CITEREFAnderson2003">Anderson 2003</a>, p. 944.</span> </li> <li id="cite_note-50"><span class="mw-cite-backlink"><b><a href="#cite_ref-50">^</a></b></span> <span class="reference-text"><a href="#CITEREFHavskovOttemöller2009">Havskov & Ottemöller 2009</a>, p. 198</span> </li> <li id="cite_note-51"><span class="mw-cite-backlink"><b><a href="#cite_ref-51">^</a></b></span> <span class="reference-text"><a href="#CITEREFHavskovOttemöller2009">Havskov & Ottemöller 2009</a>, p. 198; <a href="#CITEREFBormannWendtDi_Giacomo2013">Bormann, Wendt & Di Giacomo 2013</a>, p. 22.</span> </li> <li id="cite_note-52"><span class="mw-cite-backlink"><b><a href="#cite_ref-52">^</a></b></span> <span class="reference-text"><a href="#CITEREFBormannWendtDi_Giacomo2013">Bormann, Wendt & Di Giacomo 2013</a>, p. 23</span> </li> <li id="cite_note-53"><span class="mw-cite-backlink"><b><a href="#cite_ref-53">^</a></b></span> <span class="reference-text">NMSOP-2 <a href="#CITEREFIS_3.62012">IS 3.6 2012</a>, §7.</span> </li> <li id="cite_note-54"><span class="mw-cite-backlink"><b><a href="#cite_ref-54">^</a></b></span> <span class="reference-text">See <a href="#CITEREFBormannWendtDi_Giacomo2013">Bormann, Wendt & Di Giacomo 2013</a>, §3.2.7.2 for an extended discussion.</span> </li> <li id="cite_note-55"><span class="mw-cite-backlink"><b><a href="#cite_ref-55">^</a></b></span> <span class="reference-text">NMSOP-2 <a href="#CITEREFIS_3.62012">IS 3.6 2012</a>, §5.</span> </li> <li id="cite_note-56"><span class="mw-cite-backlink"><b><a href="#cite_ref-56">^</a></b></span> <span class="reference-text"><a href="#CITEREFBormannWendtDi_Giacomo2013">Bormann, Wendt & Di Giacomo 2013</a>, p. 131.</span> </li> <li id="cite_note-57"><span class="mw-cite-backlink"><b><a href="#cite_ref-57">^</a></b></span> <span class="reference-text"><a href="#CITEREFRautianKhalturinFujitaMackey2007">Rautian et al. 2007</a>, p. 581.</span> </li> <li id="cite_note-58"><span class="mw-cite-backlink"><b><a href="#cite_ref-58">^</a></b></span> <span class="reference-text"><a href="#CITEREFRautianKhalturinFujitaMackey2007">Rautian et al. 2007</a>; NMSOP-2 <a href="#CITEREFIS_3.72012">IS 3.7 2012</a>; <a href="#CITEREFBormannWendtDi_Giacomo2013">Bormann, Wendt & Di Giacomo 2013</a>, §3.2.4.6.</span> </li> <li id="cite_note-59"><span class="mw-cite-backlink"><b><a href="#cite_ref-59">^</a></b></span> <span class="reference-text"><a href="#CITEREFBindiParolaiOthAbdrakhmatov2011">Bindi et al. 2011</a>, p. 330. Additional regression formulas for various regions can be found in <a href="#CITEREFRautianKhalturinFujitaMackey2007">Rautian et al. 2007</a>, Tables 1 and 2. See also <a href="#CITEREFIS_3.72012">IS 3.7 2012</a>, p. 17.</span> </li> <li id="cite_note-60"><span class="mw-cite-backlink"><b><a href="#cite_ref-60">^</a></b></span> <span class="reference-text"><a href="#CITEREFRautianLeith2002">Rautian & Leith 2002</a>, p. 164.</span> </li> <li id="cite_note-61"><span class="mw-cite-backlink"><b><a href="#cite_ref-61">^</a></b></span> <span class="reference-text"><a href="#CITEREFBormannWendtDi_Giacomo2013">Bormann, Wendt & Di Giacomo 2013</a>, §3.2.6.7, p. 124.</span> </li> <li id="cite_note-62"><span class="mw-cite-backlink"><b><a href="#cite_ref-62">^</a></b></span> <span class="reference-text"><a href="#CITEREFAbe1979">Abe 1979</a>; <a href="#CITEREFAbe1989">Abe 1989</a>, p. 28. More precisely, M<sub>t</sub>  is based on far-field tsunami wave amplitudes in order to avoid some complications that happen near the source. <a href="#CITEREFAbe1979">Abe 1979</a>, p. 1566.</span> </li> <li id="cite_note-63"><span class="mw-cite-backlink"><b><a href="#cite_ref-63">^</a></b></span> <span class="reference-text"><a href="#CITEREFBlackford1984">Blackford 1984</a>, p. 29.</span> </li> <li id="cite_note-64"><span class="mw-cite-backlink"><b><a href="#cite_ref-64">^</a></b></span> <span class="reference-text"><a href="#CITEREFAbe1989">Abe 1989</a>, p. 28.</span> </li> <li id="cite_note-65"><span class="mw-cite-backlink"><b><a href="#cite_ref-65">^</a></b></span> <span class="reference-text"><a href="#CITEREFBormannWendtDi_Giacomo2013">Bormann, Wendt & Di Giacomo 2013</a>, §3.2.8.5.</span> </li> <li id="cite_note-66"><span class="mw-cite-backlink"><b><a href="#cite_ref-66">^</a></b></span> <span class="reference-text"><a href="#CITEREFBormannWendtDi_Giacomo2013">Bormann, Wendt & Di Giacomo 2013</a>, §3.2.4.5.</span> </li> <li id="cite_note-67"><span class="mw-cite-backlink"><b><a href="#cite_ref-67">^</a></b></span> <span class="reference-text"><a href="#CITEREFHavskovOttemöller2009">Havskov & Ottemöller 2009</a>, §6.3.</span> </li> <li id="cite_note-68"><span class="mw-cite-backlink"><b><a href="#cite_ref-68">^</a></b></span> <span class="reference-text"><a href="#CITEREFBormannWendtDi_Giacomo2013">Bormann, Wendt & Di Giacomo 2013</a>, §3.2.4.5, pp. 71–72.</span> </li> <li id="cite_note-69"><span class="mw-cite-backlink"><b><a href="#cite_ref-69">^</a></b></span> <span class="reference-text"><a href="#CITEREFMussonCecić2012">Musson & Cecić 2012</a>, p. 2.</span> </li> <li id="cite_note-70"><span class="mw-cite-backlink"><b><a href="#cite_ref-70">^</a></b></span> <span class="reference-text"><a href="#CITEREFGutenbergRichter1942">Gutenberg & Richter 1942</a>.</span> </li> <li id="cite_note-71"><span class="mw-cite-backlink"><b><a href="#cite_ref-71">^</a></b></span> <span class="reference-text"><a href="#CITEREFGrünthal2011">Grünthal 2011</a>, p. 240.</span> </li> <li id="cite_note-72"><span class="mw-cite-backlink"><b><a href="#cite_ref-72">^</a></b></span> <span class="reference-text"><a href="#CITEREFGrünthal2011">Grünthal 2011</a>, p. 240.</span> </li> <li id="cite_note-73"><span class="mw-cite-backlink"><b><a href="#cite_ref-73">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.usgs.gov/programs/earthquake-hazards/magnitude-types">"Magnitude Types | U.S. Geological Survey"</a>. United States Geological Survey<span class="reference-accessdate">. Retrieved <span class="nowrap">2024-04-06</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Magnitude+Types+%7C+U.S.+Geological+Survey&rft.pub=United+States+Geological+Survey&rft_id=https%3A%2F%2Fwww.usgs.gov%2Fprograms%2Fearthquake-hazards%2Fmagnitude-types&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASeismic+magnitude+scales" class="Z3988"></span></span> </li> <li id="cite_note-74"><span class="mw-cite-backlink"><b><a href="#cite_ref-74">^</a></b></span> <span class="reference-text"><a href="#CITEREFStoverCoffman1993">Stover & Coffman 1993</a>, p. 3.</span> </li> <li id="cite_note-75"><span class="mw-cite-backlink"><b><a href="#cite_ref-75">^</a></b></span> <span class="reference-text"><a href="#CITEREFEngdahlVillaseñor2002">Engdahl & Villaseñor 2002</a>.</span> </li> <li id="cite_note-76"><span class="mw-cite-backlink"><b><a href="#cite_ref-76">^</a></b></span> <span class="reference-text"><a href="#CITEREFMakrisBlack2004">Makris & Black 2004</a>, p. 1032.</span> </li> <li id="cite_note-77"><span class="mw-cite-backlink"><b><a href="#cite_ref-77">^</a></b></span> <span class="reference-text"><a href="#CITEREFDoi2010">Doi 2010</a>.</span> </li> <li id="cite_note-78"><span class="mw-cite-backlink"><b><a href="#cite_ref-78">^</a></b></span> <span class="reference-text"><a href="#CITEREFHuttonWoessnerHaukson2010">Hutton, Woessner & Haukson 2010</a>, pp. 431, 433.</span> </li> <li id="cite_note-79"><span class="mw-cite-backlink"><b><a href="#cite_ref-79">^</a></b></span> <span class="reference-text">NMSOP-2 <a href="#CITEREFIS_3.22013">IS 3.2 2013</a>, pp. 1–2.</span> </li> <li id="cite_note-80"><span class="mw-cite-backlink"><b><a href="#cite_ref-80">^</a></b></span> <span class="reference-text"><a href="#CITEREFAbe1981">Abe 1981</a>, p. 74; <a href="#CITEREFEngdahlVillaseñor2002">Engdahl & Villaseñor 2002</a>, p. 667.</span> </li> <li id="cite_note-81"><span class="mw-cite-backlink"><b><a href="#cite_ref-81">^</a></b></span> <span class="reference-text"><a href="#CITEREFEngdahlVillaseñor2002">Engdahl & Villaseñor 2002</a>, p. 688.</span> </li> <li id="cite_note-82"><span class="mw-cite-backlink"><b><a href="#cite_ref-82">^</a></b></span> <span class="reference-text"><a href="#CITEREFAbeNoguchi1983">Abe & Noguchi 1983</a>.</span> </li> <li id="cite_note-83"><span class="mw-cite-backlink"><b><a href="#cite_ref-83">^</a></b></span> <span class="reference-text"><a href="#CITEREFAbe1981">Abe 1981</a>, p. 72.</span> </li> <li id="cite_note-84"><span class="mw-cite-backlink"><b><a href="#cite_ref-84">^</a></b></span> <span class="reference-text">Defined as "a weighted mean between <i>M</i><sub>B</sub> and <i>M</i><sub>S</sub>." <a href="#CITEREFGutenbergRichter1956">Gutenberg & Richter 1956</a>, p. 1.</span> </li> <li id="cite_note-85"><span class="mw-cite-backlink"><b><a href="#cite_ref-85">^</a></b></span> <span class="reference-text">"At Pasadena, a weighted mean is taken between <i>m</i><sub>S</sub> as found directly from body waves, and <i>m</i><sub>S</sub>, the corresponding value derived from <i>M</i><sub>S</sub> ...." <a href="#CITEREFGutenbergRichter1956">Gutenberg & Richter 1956</a>, p. 2.</span> </li> <li id="cite_note-86"><span class="mw-cite-backlink"><b><a href="#cite_ref-86">^</a></b></span> <span class="reference-text">E.g., <a href="#CITEREFKanamori1977">Kanamori 1977</a>.</span> </li> </ol></div></div> <div class="mw-heading mw-heading2"><h2 id="General_and_cited_sources">General and cited sources</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Seismic_magnitude_scales&action=edit&section=19" title="Edit section: General and cited sources"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239549316"><div class="refbegin refbegin-columns references-column-width" style="column-width: 30em"> <ul><li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFAbe1979" class="citation cs2">Abe, K. (April 1979), "Size of great earthquakes of 1837–1874 inferred from tsunami data", <i>Journal of Geophysical Research</i>, <b>84</b> (B4): 1561–1568, <a href="/wiki/Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/1979JGR....84.1561A">1979JGR....84.1561A</a>, <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1029%2FJB084iB04p01561">10.1029/JB084iB04p01561</a></cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Journal+of+Geophysical+Research&rft.atitle=Size+of+great+earthquakes+of+1837%E2%80%931874+inferred+from+tsunami+data&rft.volume=84&rft.issue=B4&rft.pages=1561-1568&rft.date=1979-04&rft_id=info%3Adoi%2F10.1029%2FJB084iB04p01561&rft_id=info%3Abibcode%2F1979JGR....84.1561A&rft.aulast=Abe&rft.aufirst=K.&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASeismic+magnitude+scales" class="Z3988"></span>.</li></ul> <ul><li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFAbe1981" class="citation cs2">Abe, K. (October 1981), "Magnitudes of large shallow earthquakes from 1904 to 1980", <i>Physics of the Earth and Planetary Interiors</i>, <b>27</b> (1): 72–92, <a href="/wiki/Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/1981PEPI...27...72A">1981PEPI...27...72A</a>, <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1016%2F0031-9201%2881%2990088-1">10.1016/0031-9201(81)90088-1</a></cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Physics+of+the+Earth+and+Planetary+Interiors&rft.atitle=Magnitudes+of+large+shallow+earthquakes+from+1904+to+1980&rft.volume=27&rft.issue=1&rft.pages=72-92&rft.date=1981-10&rft_id=info%3Adoi%2F10.1016%2F0031-9201%2881%2990088-1&rft_id=info%3Abibcode%2F1981PEPI...27...72A&rft.aulast=Abe&rft.aufirst=K.&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASeismic+magnitude+scales" class="Z3988"></span>.</li></ul> <ul><li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFAbe1989" class="citation cs2">Abe, K. (September 1989), "Quantification of tsunamigenic earthquakes by the <i>M<sub>t</sub></i> scale", <i>Tectonophysics</i>, <b>166</b> (1–3): 27–34, <a href="/wiki/Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/1989Tectp.166...27A">1989Tectp.166...27A</a>, <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1016%2F0040-1951%2889%2990202-3">10.1016/0040-1951(89)90202-3</a></cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Tectonophysics&rft.atitle=Quantification+of+tsunamigenic+earthquakes+by+the+M%3Csub%3Et%3C%2Fsub%3E+scale&rft.volume=166&rft.issue=1%E2%80%933&rft.pages=27-34&rft.date=1989-09&rft_id=info%3Adoi%2F10.1016%2F0040-1951%2889%2990202-3&rft_id=info%3Abibcode%2F1989Tectp.166...27A&rft.aulast=Abe&rft.aufirst=K.&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASeismic+magnitude+scales" class="Z3988"></span>.</li></ul> <ul><li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFAbeNoguchi1983" class="citation cs2">Abe, K; Noguchi, S. (August 1983), "Revision of magnitudes of large shallow earthquakes, 1897-1912", <i>Physics of the Earth and Planetary Interiors</i>, <b>33</b> (1): 1–11, <a href="/wiki/Bibcode_(identifier)" class="mw-redirect" title="Bibcode (identifier)">Bibcode</a>:<a rel="nofollow" class="external text" href="https://ui.adsabs.harvard.edu/abs/1983PEPI...33....1A">1983PEPI...33....1A</a>, <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1016%2F0031-9201%2883%2990002-X">10.1016/0031-9201(83)90002-X</a></cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Physics+of+the+Earth+and+Planetary+Interiors&rft.atitle=Revision+of+magnitudes+of+large+shallow+earthquakes%2C+1897-1912&rft.volume=33&rft.issue=1&rft.pages=1-11&rft.date=1983-08&rft_id=info%3Adoi%2F10.1016%2F0031-9201%2883%2990002-X&rft_id=info%3Abibcode%2F1983PEPI...33....1A&rft.aulast=Abe&rft.aufirst=K&rft.au=Noguchi%2C+S.&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASeismic+magnitude+scales" class="Z3988"></span>.</li></ul> <ul><li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFAnderson2003" class="citation cs2">Anderson, J. G. (2003), "Chapter 57: Strong-Motion Seismology", <a rel="nofollow" class="external text" href="https://books.google.com/books?id=qWmwnHIW5HUC"><i>International Handbook of Earthquake & Engineering Seismology, Part B</i></a>, pp. 937–966, <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/0-12-440658-0" title="Special:BookSources/0-12-440658-0"><bdi>0-12-440658-0</bdi></a></cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=bookitem&rft.atitle=Chapter+57%3A+Strong-Motion+Seismology&rft.btitle=International+Handbook+of+Earthquake+%26+Engineering+Seismology%2C+Part+B&rft.pages=937-966&rft.date=2003&rft.isbn=0-12-440658-0&rft.aulast=Anderson&rft.aufirst=J.+G.&rft_id=https%3A%2F%2Fbooks.google.com%2Fbooks%3Fid%3DqWmwnHIW5HUC&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASeismic+magnitude+scales" class="Z3988"></span>.</li></ul> <ul><li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFBindiParolaiOthAbdrakhmatov2011" class="citation cs2">Bindi, D.; Parolai, S.; Oth, K.; Abdrakhmatov, A.; Muraliev, A.; Zschau, J. 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Also available <a rel="nofollow" class="external text" href="http://www.isc.ac.uk/iscbulletin/agencies/JMA-ops.pdf">here</a> (sections renumbered).</li></ul> <ul><li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFEngdahlVillaseñor2002" class="citation cs2 cs1-prop-long-vol">Engdahl, E. R.; Villaseñor, A. (2002), "Chapter 41: Global Seismicity: 1900–1999", in Lee, W.H.K.; Kanamori, H.; Jennings, P.C.; Kisslinger, C. 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(1993), <a rel="nofollow" class="external text" href="http://dggs.alaska.gov/webpubs/usgs/p/text/p1527.pdf"><i>Seismicity of the United States, 1568–1989 (Revised)</i></a> <span class="cs1-format">(PDF)</span>, U.S. Geological Survey Professional Paper 1527</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Seismicity+of+the+United+States%2C+1568%E2%80%931989+%28Revised%29&rft.series=U.S.+Geological+Survey+Professional+Paper+1527&rft.date=1993&rft.aulast=Stover&rft.aufirst=C.+W.&rft.au=Coffman%2C+J.+L.&rft_id=http%3A%2F%2Fdggs.alaska.gov%2Fwebpubs%2Fusgs%2Fp%2Ftext%2Fp1527.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3ASeismic+magnitude+scales" class="Z3988"></span>.</li></ul> </div> <div class="mw-heading mw-heading2"><h2 id="External_links">External links</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Seismic_magnitude_scales&action=edit&section=20" title="Edit section: External links"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a rel="nofollow" class="external text" href="https://www.youtube.com/watch?v=YXMKSOsv3QA">Perspective: a graphical comparison of earthquake energy release</a> – <a href="/wiki/Pacific_Tsunami_Warning_Center" title="Pacific Tsunami Warning Center">Pacific Tsunami Warning Center</a></li> <li><a rel="nofollow" class="external text" href="https://earthquake.usgs.gov/data/shakemap/">USGS ShakeMap</a> Providing near-real-time maps of ground motion and shaking intensity following significant earthquakes.</li></ul> <div class="navbox-styles"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><style data-mw-deduplicate="TemplateStyles:r1236075235">.mw-parser-output .navbox{box-sizing:border-box;border:1px solid #a2a9b1;width:100%;clear:both;font-size:88%;text-align:center;padding:1px;margin:1em auto 0}.mw-parser-output .navbox 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style="padding:3px"><table class="nowraplinks mw-collapsible autocollapse navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239400231"><div class="navbar plainlinks hlist navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:Seismic_scales" title="Template:Seismic scales"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:Seismic_scales" title="Template talk:Seismic scales"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:Seismic_scales" title="Special:EditPage/Template:Seismic scales"><abbr title="Edit this template">e</abbr></a></li></ul></div><div id="Seismic_magnitude_scales" style="font-size:114%;margin:0 4em"><a class="mw-selflink selflink">Seismic magnitude scales</a></div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%">Modern scales</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%">Intensity scales</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Central_Weather_Administration_seismic_intensity_scale" title="Central Weather Administration seismic intensity scale">Central Weather Administration seismic intensity scale</a></li> <li><a href="/wiki/Environmental_Seismic_Intensity_scale" title="Environmental Seismic Intensity scale">Environmental Seismic Intensity scale (ESI)</a></li> <li><a href="/wiki/European_macroseismic_scale" title="European macroseismic scale">European Macroseismic Scale (EMS)</a></li> <li><a href="/wiki/China_seismic_intensity_scale" title="China seismic intensity scale">Chinese</a></li> <li><a href="/wiki/Medvedev%E2%80%93Sponheuer%E2%80%93Karnik_scale" title="Medvedev–Sponheuer–Karnik scale">Medvedev–Sponheuer–Karnik (MSK)</a></li> <li><a href="/wiki/Modified_Mercalli_intensity_scale" title="Modified Mercalli intensity scale">Modified Mercalli (MM)</a></li> <li><a href="/wiki/PHIVOLCS_Earthquake_Intensity_Scale" class="mw-redirect" title="PHIVOLCS Earthquake Intensity Scale">PHIVOLCS Earthquake Intensity Scale (PEIS)</a></li> <li><a href="/wiki/Japan_Meteorological_Agency_seismic_intensity_scale" title="Japan Meteorological Agency seismic intensity scale">Shindo (Japanese)</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Magnitude scales</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Body-wave_magnitude" class="mw-redirect" title="Body-wave magnitude">Body-wave magnitude</a></li> <li><a href="/wiki/Earthquake_duration_magnitude" title="Earthquake duration magnitude">Duration magnitude</a></li> <li><a href="/wiki/Richter_scale" title="Richter scale">Local magnitude (Richter scale)</a></li> <li><a href="/wiki/Moment_magnitude_scale" title="Moment magnitude scale">Moment magnitude</a></li> <li><a href="/wiki/Surface-wave_magnitude" title="Surface-wave magnitude">Surface-wave magnitude</a></li> <li><a href="/wiki/Energy_class" title="Energy class">Energy class</a> (K-class)</li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Historical scales</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Medvedev%E2%80%93Sponheuer%E2%80%93Karnik_scale" title="Medvedev–Sponheuer–Karnik scale">GEOFIAN</a></li> <li><a href="/wiki/Modified_Mercalli_intensity_scale#History" title="Modified Mercalli intensity scale">Mercalli–Cancani–Sieberg (MCS)</a></li> <li><a href="/wiki/Modified_Mercalli_intensity_scale#History" title="Modified Mercalli intensity scale">Mercalli–Wood–Neuman (MWN)</a></li> <li><a href="/w/index.php?title=Omori_scale&action=edit&redlink=1" class="new" title="Omori scale (page does not exist)">Omori</a></li> <li><a href="/wiki/Rossi%E2%80%93Forel_scale" title="Rossi–Forel scale">Rossi–Forel</a></li></ul> </div></td></tr></tbody></table></div>    </div><noscript><img src="https://login.wikimedia.org/wiki/Special:CentralAutoLogin/start?type=1x1&useformat=desktop" alt="" width="1" height="1" style="border: none; position: absolute;"></noscript> <div class="printfooter" data-nosnippet="">Retrieved from "<a dir="ltr" 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Me magnitude scale">Articles using Me magnitude scale</a></li><li><a href="/wiki/Category:Articles_using_Mwp_magnitude_scale_with_duration" title="Category:Articles using Mwp magnitude scale with duration">Articles using Mwp magnitude scale with duration</a></li><li><a href="/wiki/Category:Articles_using_mBc_magnitude_scale" title="Category:Articles using mBc magnitude scale">Articles using mBc magnitude scale</a></li><li><a href="/wiki/Category:Articles_using_Mgr_magnitude_scale" title="Category:Articles using Mgr magnitude scale">Articles using Mgr magnitude scale</a></li><li><a href="/wiki/Category:All_articles_with_dead_external_links" title="Category:All articles with dead external links">All articles with dead external links</a></li><li><a href="/wiki/Category:Articles_with_dead_external_links_from_October_2023" title="Category:Articles with dead external links from October 2023">Articles with dead external links from October 2023</a></li><li><a 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[\"CITEREFEX_3.12012\"] = 1,\n [\"CITEREFEngdahlVillaseñor2002\"] = 1,\n [\"CITEREFFrankel1994\"] = 1,\n [\"CITEREFGrünthal2011\"] = 1,\n [\"CITEREFGutenberg1945a\"] = 1,\n [\"CITEREFGutenberg1945c\"] = 1,\n [\"CITEREFGutenbergRichter1936\"] = 1,\n [\"CITEREFGutenbergRichter1942\"] = 1,\n [\"CITEREFGutenbergRichter1954\"] = 1,\n [\"CITEREFGutenbergRichter1956\"] = 1,\n [\"CITEREFHanks1979\"] = 1,\n [\"CITEREFHavskovOttemöller2009\"] = 1,\n [\"CITEREFHough2007\"] = 1,\n [\"CITEREFHuttonBoore1987\"] = 1,\n [\"CITEREFHuttonWoessnerHaukson2010\"] = 1,\n [\"CITEREFIS_3.22013\"] = 1,\n [\"CITEREFIS_3.32014\"] = 1,\n [\"CITEREFIS_3.62012\"] = 1,\n [\"CITEREFIS_3.72012\"] = 1,\n [\"CITEREFJohnston1996\"] = 1,\n [\"CITEREFKanamori1977\"] = 1,\n [\"CITEREFKanamori1983\"] = 1,\n [\"CITEREFKatsumata1996\"] = 1,\n [\"CITEREFMakrisBlack2004\"] = 1,\n [\"CITEREFMussonCecić2012\"] = 1,\n [\"CITEREFNuttli1973\"] = 1,\n [\"CITEREFNuttli1983\"] = 1,\n [\"CITEREFRautianKhalturinFujitaMackey2007\"] = 1,\n [\"CITEREFRautianLeith2002\"] = 1,\n [\"CITEREFRichter1935\"] = 1,\n [\"CITEREFSpenceSipkinChoy1989\"] = 1,\n [\"CITEREFStoverCoffman1993\"] = 1,\n [\"K\"] = 1,\n [\"Local_magnitude_scale\"] = 1,\n [\"M0\"] = 1,\n [\"MI\"] = 1,\n [\"MJMA\"] = 1,\n [\"MK\"] = 1,\n [\"ML\"] = 1,\n [\"MLH\"] = 1,\n [\"Mc\"] = 1,\n [\"Md\"] = 1,\n [\"Me\"] = 1,\n [\"Mfa\"] = 1,\n [\"Mgr\"] = 1,\n [\"Mh\"] = 1,\n [\"Mi\"] = 1,\n [\"Mjma\"] = 1,\n [\"Mk\"] = 1,\n [\"Ml\"] = 1,\n [\"Mla\"] = 1,\n [\"Mm\"] = 1,\n [\"Mms\"] = 1,\n [\"Ms\"] = 1,\n [\"Ms20\"] = 1,\n [\"Ms7\"] = 1,\n [\"Msbb\"] = 1,\n [\"Msn\"] = 1,\n [\"Mt\"] = 1,\n [\"Muk\"] = 1,\n [\"Mw\"] = 1,\n [\"Mwb\"] = 1,\n [\"Mwbc\"] = 1,\n [\"Mwc\"] = 1,\n [\"Mwp\"] = 1,\n [\"Mwpd\"] = 1,\n [\"Mwr\"] = 1,\n [\"Mww\"] = 1,\n [\"Nuttli\"] = 1,\n [\"Richter\"] = 1,\n [\"Two_quakes\"] = 1,\n [\"UK\"] = 1,\n [\"mB\"] = 1,\n [\"mN\"] = 1,\n [\"magnitude\"] = 1,\n [\"mb\"] = 1,\n [\"mbLg\"] = 1,\n}\ntemplate_list = table#1 {\n [\"!\"] = 1,\n [\"0\"] = 1,\n [\"Anchor\"] = 14,\n [\"Authority control\"] = 1,\n [\"Bots\"] = 1,\n [\"Cbignore\"] = 1,\n [\"Citation\"] = 48,\n [\"Cite journal\"] = 1,\n [\"Cite web\"] = 1,\n [\"Dead link\"] = 4,\n [\"EQ-isc-link\"] = 2,\n [\"Earthquakes\"] = 1,\n [\"Harnvb\"] = 2,\n [\"Harvnb\"] = 106,\n [\"Harvtxt\"] = 5,\n [\"M\"] = 44,\n [\"Main\"] = 7,\n [\"Nbsp\"] = 6,\n [\"Nowrap\"] = 2,\n [\"Refbegin\"] = 2,\n [\"Refend\"] = 2,\n [\"Reflist\"] = 1,\n [\"Seismic scales\"] = 1,\n [\"Short description\"] = 1,\n [\"Slink\"] = 1,\n [\"Sub\"] = 5,\n [\"Vanchor\"] = 1,\n [\"Webarchive\"] = 1,\n}\narticle_whitelist = table#1 {\n}\nciteref_patterns = table#1 {\n}\n"},"cachereport":{"origin":"mw-api-ext.codfw.main-854d6f764f-mrxbc","timestamp":"20241204014501","ttl":2592000,"transientcontent":false}}});});</script> <script type="application/ld+json">{"@context":"https:\/\/schema.org","@type":"Article","name":"Seismic magnitude 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