{"id":76829,"date":"2026-01-21T11:06:32","date_gmt":"2026-01-21T18:06:32","guid":{"rendered":"https:\/\/in.nau.edu\/news\/?p=76829"},"modified":"2026-01-21T11:06:32","modified_gmt":"2026-01-21T18:06:32","slug":"japan-earthquake-study","status":"publish","type":"post","link":"https:\/\/in.nau.edu\/news\/japan-earthquake-study\/","title":{"rendered":"New seafloor study reveals one reason why Japan\u2019s 2011 earthquake turned deadly"},"content":{"rendered":"<p><span data-contrast=\"none\">A new study from the bottom of the Pacific Ocean has partly revealed why the 2011 Japan earthquake and tsunami were so devastating\u2014and how scientists may be able to better understand intense disasters in the future.<\/span><span data-ccp-props=\"{&quot;201341983&quot;:0,&quot;335559739&quot;:0,&quot;335559740&quot;:240}\">\u00a0<\/span><\/p>\n<p><span data-contrast=\"none\">The study, co-authored by NAU\u00a0associate\u00a0professor <strong>Christine\u00a0Regalla\u00a0<\/strong>of the School of Earth and Sustainability, found that at the Japan Trench\u2014a deep ocean boundary where one tectonic plate dives beneath another\u2014the fault zone narrows into a thin, clay-rich layer hidden just beneath the seafloor. That weak layer enabled the 2011 \u201cmegathrust\u201d earthquake to rupture all the way to the trench, producing 130-200 feet of shallow slip and displacing\u00a0large portions\u00a0of the seafloor.<\/span><\/p>\n<p><span data-contrast=\"none\">\u201cThat\u2019s equivalent to the entire area between Los Angeles and San Francisco moving 130 to 200 feet in just six minutes,\u201d\u00a0Regalla\u00a0said. \u201cWe\u2019ve\u00a0never seen anything like that in the time\u00a0we\u2019ve\u00a0been\u00a0observing\u00a0earthquakes. Based on what we understood, we\u00a0didn\u2019t\u00a0think that could happen.\u201d<\/span><span data-ccp-props=\"{&quot;201341983&quot;:0,&quot;335559739&quot;:0,&quot;335559740&quot;:240}\">\u00a0<\/span><\/p>\n<p><iframe loading=\"lazy\" title=\"IODP Expedition 405 &quot;JTRACK: The Story of Stress&quot;\" width=\"640\" height=\"360\" src=\"https:\/\/www.youtube.com\/embed\/qoBNd8R0Mik?feature=oembed\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" referrerpolicy=\"strict-origin-when-cross-origin\" allowfullscreen><\/iframe><\/p>\n<p><span data-contrast=\"none\">The geologist explained that when tectonic plates move, causing earthquakes, parts of the plates typically rupture very deep underground. For example, the\u00a0plate\u00a0rupture that started the 6.8-magnitude Nisqually earthquake in the Pacific Northwest in 2001 was about 32 miles under the seafloor. But the 2011 earthquake was different:\u00a0Tthe\u00a0Japan Trench rupture was just 15 miles deep, much closer to the seafloor. The resulting 9.1-magnitude earthquake and major tsunami was one of the deadliest natural disasters in modern Japanese history, killing\u00a0nearly\u00a020,000\u00a0people\u00a0and causing more than\u00a0$200 billion\u00a0in damage.<\/span><span data-ccp-props=\"{&quot;201341983&quot;:0,&quot;335559739&quot;:0,&quot;335559740&quot;:240}\">\u00a0<\/span><\/p>\n<p><span data-contrast=\"none\">Regalla\u00a0and her colleagues discovered the weak layer of sediment at the Japan Trench by taking the research vessel\u00a0Chikyu\u00a0to the western Pacific, drilling\u00a026,000 feet\u00a0deep into the ocean floor and analyzing the extracted material. The effort was recognized by<\/span><a href=\"https:\/\/www.guinnessworldrecords.com\/world-records\/777662-deepest-scientific-ocean-drilling\"><span data-contrast=\"none\">\u00a0Guinness World Records<\/span><\/a><span data-contrast=\"none\">\u00a0as the deepest scientific ocean drilling ever conducted.<\/span><span data-ccp-props=\"{&quot;201341983&quot;:0,&quot;335559739&quot;:0,&quot;335559740&quot;:240}\">\u00a0<\/span><\/p>\n<p><span data-contrast=\"none\">The sediment samples recovered from the drilling operation revealed a 100-foot-thick layer of pelagic\u00a0clay,\u00a0a very soft\u00a0and slippery material formed from microscopic particles that slowly settled to the seafloor over millions of years. With stronger layers surrounding it, the clay acted like a natural \u201ctear line\u201d that concentrated the rupture along that surface.<\/span><span data-ccp-props=\"{&quot;201341983&quot;:0,&quot;335559739&quot;:0,&quot;335559740&quot;:240}\">\u00a0<\/span><\/p>\n<p><span data-contrast=\"none\">\u201cAt the Japan Trench, the geologic layering basically predetermines where the fault will form,\u201d said study co-author<\/span><a href=\"https:\/\/www.engineering.cornell.edu\/people\/patrick-fulton\/\"><span data-contrast=\"none\">\u00a0Patrick Fulton<\/span><\/a><span data-contrast=\"none\">, an associate professor in the Department of Earth and Atmospheric Sciences at Cornell University. \u201cIt becomes an extremely focused, extremely weak surface, which makes it easier for ruptures to propagate all the way to the seafloor.\u201d<\/span><\/p>\n<figure id=\"attachment_76831\" aria-describedby=\"caption-attachment-76831\" style=\"width: 450px\" class=\"wp-caption alignright\"><a href=\"http:\/\/in.nau.edu\/news\/wordpresst\/uploads\/sites\/153\/wp-content\/uploads\/2026\/01\/DailyPhoto_20241105_1.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-76831\" src=\"http:\/\/in.nau.edu\/news\/wordpresst\/uploads\/sites\/153\/wp-content\/uploads\/2026\/01\/DailyPhoto_20241105_1.jpg\" alt=\"Christine Regalla in PPE with one other researcher posing in front of a sediment funneling machine\" width=\"450\" height=\"439\" srcset=\"https:\/\/in.nau.edu\/wp-content\/uploads\/sites\/402\/2026\/01\/DailyPhoto_20241105_1.jpg 907w, https:\/\/in.nau.edu\/wp-content\/uploads\/sites\/402\/2026\/01\/DailyPhoto_20241105_1-300x293.jpg 300w, https:\/\/in.nau.edu\/wp-content\/uploads\/sites\/402\/2026\/01\/DailyPhoto_20241105_1-768x749.jpg 768w\" sizes=\"auto, (max-width: 450px) 100vw, 450px\" \/><\/a><figcaption id=\"caption-attachment-76831\" class=\"wp-caption-text\">Regalla, pictured at bottom, and her colleagues drilled 26,000 feet deep into the ocean floor and analyzed the extracted material.<\/figcaption><\/figure>\n<p><span data-contrast=\"none\">The study, authored by\u00a0Regalla\u00a0and more than a dozen other scientists from across the globe,<\/span><a href=\"https:\/\/www.science.org\/doi\/10.1126\/science.ady0234\"><span data-contrast=\"none\">\u00a0was published in December in Science<\/span><\/a><span data-contrast=\"none\">.<\/span><span data-ccp-props=\"{&quot;201341983&quot;:0,&quot;335559739&quot;:0,&quot;335559740&quot;:240}\">\u00a0<\/span><\/p>\n<p><span data-contrast=\"none\">Because the pelagic clay layer extends for hundreds of miles along the Japan Trench, the region may be more prone to shallow-slip earthquakes than previously recognized. That will be\u00a0important for geologists to dig further into,\u00a0Regalla\u00a0said, because major natural disasters can have ripple effects beyond their countries of origin.<\/span><span data-ccp-props=\"{&quot;201341983&quot;:0,&quot;335559739&quot;:0,&quot;335559740&quot;:240}\">\u00a0<\/span><\/p>\n<p><span data-contrast=\"none\">\u201cAn earthquake and tsunami in Japan\u00a0doesn\u2019t\u00a0just impact people who live locally\u2014it also impacts people at the ports and people who live across the ocean,\u201d\u00a0Regalla\u00a0said. \u201cThink about Hawaii: Their most devastating tsunamis come from Japan and Alaska. These are truly global events.\u201d<\/span><span data-ccp-props=\"{&quot;201341983&quot;:0,&quot;335559739&quot;:0,&quot;335559740&quot;:240}\">\u00a0<\/span><\/p>\n<p><span data-contrast=\"none\">Regalla\u00a0said she and her co-authors hope their work will help scientists better understand and better forecast large-magnitude earthquakes and tsunamis by\u00a0identifying\u00a0the locations that are most susceptible. Policymakers could use those scientific findings to alter building codes, build earthquake-proof infrastructure, revise their evacuation\u00a0plans\u00a0and more, helping communities become more resilient.<\/span><span data-ccp-props=\"{&quot;201341983&quot;:0,&quot;335559739&quot;:0,&quot;335559740&quot;:240}\">\u00a0<\/span><span data-ccp-props=\"{&quot;201341983&quot;:0,&quot;335559739&quot;:0,&quot;335559740&quot;:240}\">\u00a0<\/span><\/p>\n<p><span data-contrast=\"none\">\u201cJapan is one of the world leaders in earthquake and tsunami preparation, but even they weren\u2019t prepared for what happened in 2011,\u201d\u00a0Regalla\u00a0said. \u201cWe all need to gain a better understanding of where these events might happen in the future. Only then can we make emergency plans that will keep everyone safe.\u201d<\/span><span data-ccp-props=\"{&quot;201341983&quot;:0,&quot;335559739&quot;:0,&quot;335559740&quot;:240}\">\u00a0<\/span><\/p>\n<p><span data-ccp-props=\"{}\"><img loading=\"lazy\" decoding=\"async\" class=\"alignleft wp-image-56007\" src=\"http:\/\/in.nau.edu\/news\/wordpresst\/uploads\/sites\/153\/wp-content\/uploads\/2019\/06\/NAU_primary-281_3514.png\" alt=\"Northern Arizona University Logo\" width=\"134\" height=\"95\" srcset=\"https:\/\/in.nau.edu\/wp-content\/uploads\/sites\/402\/2019\/06\/NAU_primary-281_3514.png 905w, https:\/\/in.nau.edu\/wp-content\/uploads\/sites\/402\/2019\/06\/NAU_primary-281_3514-300x213.png 300w, https:\/\/in.nau.edu\/wp-content\/uploads\/sites\/402\/2019\/06\/NAU_primary-281_3514-768x546.png 768w, https:\/\/in.nau.edu\/wp-content\/uploads\/sites\/402\/2019\/06\/NAU_primary-281_3514-600x426.png 600w\" sizes=\"auto, (max-width: 134px) 100vw, 134px\" \/><\/span><\/p>\n<p><span data-ccp-props=\"{}\"><br \/>\nJill Kimball | NAU Communications<br \/>\n(928) 523-2282 | <a href=\"mailto:jill.kimball@nau.edu\">jill.kimball@nau.edu<\/a><\/span><\/p>\n","protected":false},"excerpt":{"rendered":"<p><a class=\"search-results-excerpt-link\" href=\"https:\/\/in.nau.edu\/news\/japan-earthquake-study\/\">A new study from the bottom of the Pacific Ocean has partly revealed why the 2011 Japan earthquake and tsunami were so devastating\u2014and how scientists may be able to better understand intense disasters in the future.\u00a0 The study, co-authored by NAU\u00a0associate\u00a0professor Christine\u00a0Regalla\u00a0of the School of Earth and Sustainability, found that at the Japan Trench\u2014a deep&hellip;<\/a><\/p>\n","protected":false},"author":95,"featured_media":76830,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[11],"tags":[],"class_list":["post-76829","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-research-academics"],"acf":[],"_links":{"self":[{"href":"https:\/\/in.nau.edu\/news\/wp-json\/wp\/v2\/posts\/76829","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/in.nau.edu\/news\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/in.nau.edu\/news\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/in.nau.edu\/news\/wp-json\/wp\/v2\/users\/95"}],"replies":[{"embeddable":true,"href":"https:\/\/in.nau.edu\/news\/wp-json\/wp\/v2\/comments?post=76829"}],"version-history":[{"count":0,"href":"https:\/\/in.nau.edu\/news\/wp-json\/wp\/v2\/posts\/76829\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/in.nau.edu\/news\/wp-json\/wp\/v2\/media\/76830"}],"wp:attachment":[{"href":"https:\/\/in.nau.edu\/news\/wp-json\/wp\/v2\/media?parent=76829"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/in.nau.edu\/news\/wp-json\/wp\/v2\/categories?post=76829"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/in.nau.edu\/news\/wp-json\/wp\/v2\/tags?post=76829"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}