{"id":65252,"date":"2026-06-25T09:15:24","date_gmt":"2026-06-25T06:15:24","guid":{"rendered":"https:\/\/geoconversation.org\/news\/seismic-wave-bounced-off-earths-core-and-shifted-japan-eastward\/"},"modified":"2026-06-25T09:22:19","modified_gmt":"2026-06-25T06:22:19","slug":"seismic-wave-bounced-off-earths-core-and-shifted-japan-eastward","status":"publish","type":"news","link":"https:\/\/geoconversation.org\/en\/news\/seismic-wave-bounced-off-earths-core-and-shifted-japan-eastward\/","title":{"rendered":"Seismic Wave Bounced Off Earth&#8217;s Core and Shifted Japan Eastward"},"content":{"rendered":"\n<p class=\"wp-block-paragraph\">The devastating 2011 earthquake in Japan left scientists with a mystery that took years to solve. About 15 minutes after the initial shock, the entire country shifted slightly eastward. The cause was a seismic wave that traveled to the center of the Earth, reflected off the liquid outer core, and returned to the surface.  <\/p>\n\n<p class=\"wp-block-paragraph\">The study was led by University of Chicago geophysicist Sanyun Park. She investigated unusual GPS observations recorded on March 11, 2011. Approximately 15 minutes after the earthquake began, nearly all of Japan\u2014from Hokkaido to Kyushu, spanning about 3,000 kilometers\u2014shifted eastward by five to six millimeters.  <\/p>\n\n<p class=\"wp-block-paragraph\">At first, researchers suspected the signals were caused by <a href=\"https:\/\/geoconversation.org\/en\/geophysical-equipment-wont-be-the-same-how-small-hardware-ateliers-are-changing-field-prospecting\/\" data-type=\"link\" data-id=\"https:\/\/geoconversation.org\/geofizicheskoe-oborudovanie-buduschee\/\" target=\"_blank\" rel=\"noopener\">instrument errors<\/a>. However, Park noticed that the displacement was remarkably uniform across the entire country and did not coincide with either the main shock or the earliest aftershocks. <\/p>\n\n<p class=\"wp-block-paragraph\">After years of data analysis, the research team reached a conclusion once considered impossible. Seismic waves generated by the earthquake traveled down to Earth&#8217;s liquid outer core, reflected from it, and propagated back to the crust, causing the simultaneous movement of four tectonic plates. Seismologists had long believed that the energy of such waves dissipated deep within the Earth before it could return to the surface. The new findings challenge that assumption.   <\/p>\n\n<p class=\"wp-block-paragraph\">According to the researchers, the returning wave released energy comparable to a magnitude 7.5 earthquake. However, because the energy was distributed across an enormous area, the motion was much weaker and caused no distinct additional damage. Against the backdrop of the 2011 disaster\u2014which claimed about 20,000 lives, triggered a devastating tsunami, and led to the Fukushima nuclear crisis\u2014the subtle displacement went completely unnoticed.  <\/p>\n\n<p class=\"wp-block-paragraph\">The discovery also has practical implications. The round trip from the Earth&#8217;s surface to the core and back takes about 15 minutes, creating a predictable time window that could enhance earthquake warning systems. Unlike sudden aftershocks, this type of seismic signal arrives with a measurable delay. Park believes emergency planners and policymakers should take this newly identified <a href=\"https:\/\/geoconversation.org\/en\/artificial-intelligence-in-seismic-exploration-how-geophysicists-work-is-changing\/\" data-type=\"link\" data-id=\"https:\/\/geoconversation.org\/ai-seismic-interpretation\/\" target=\"_blank\" rel=\"noopener\">seismic phenomenon<\/a> into account.   <\/p>\n\n<p class=\"wp-block-paragraph\">Independent experts have welcomed the findings. Columbia University geophysicist G\u00f6ran Ekstr\u00f6m noted that the main earthquake shifted Honshu Island by approximately 20 centimeters. University of Maryland professor Vedran Lekic emphasized that the phenomenon could only be detected thanks to Japan&#8217;s exceptionally dense geophysical monitoring network. In regions with less sophisticated instrumentation, similar events would likely go unnoticed.   <\/p>\n\n<p class=\"wp-block-paragraph\">The study adds a new dimension to scientists&#8217; understanding of how major earthquakes affect the planet. Large seismic events continue to influence Earth&#8217;s interior and surface for many minutes after the main rupture, sometimes in unexpected ways. <\/p>\n\n<p class=\"has-text-align-right has-small-font-size wp-block-paragraph\">Source: CNN<\/p>\n\n<p class=\"has-text-align-right has-small-font-size wp-block-paragraph\">Image: Koji Ueda<\/p>\n","protected":false},"excerpt":{"rendered":"<p>The devastating 2011 earthquake in Japan left scientists with a mystery that took years to solve. About 15 minutes after the initial shock, the entire country shifted slightly eastward. The cause was a seismic wave that traveled to the center of the Earth, reflected off the liquid outer core, and returned to the surface. The [&hellip;]<\/p>\n","protected":false},"author":12,"featured_media":65251,"comment_status":"open","ping_status":"closed","template":"","meta":{"_acf_changed":false,"_seopress_robots_primary_cat":"","_seopress_titles_title":"Seismic Wave Bounced Off Earth's Core and Shifted Japan Eastward in 2011","_seopress_titles_desc":"Scientists discovered that a seismic wave reflected from Earth's core and uniformly shifted Japan eastward. Learn about this newly identified type of predictable seismic hazard.<br\/> ","_seopress_robots_index":"","_seopress_analysis_target_kw":"","footnotes":""},"categories":[559],"tags":[655,656],"class_list":["post-65252","news","type-news","status-publish","has-post-thumbnail","category-geophysics","tag-geophysics","tag-tectonics"],"acf":[],"pbg_featured_image_src":{"full":["https:\/\/geoconversation.org\/wp-content\/uploads\/2026\/06\/otrazhenie-volny-ot-yadra-sdvih-yaponii.webp",1440,912,false],"thumbnail":["https:\/\/geoconversation.org\/wp-content\/uploads\/2026\/06\/otrazhenie-volny-ot-yadra-sdvih-yaponii-150x95.webp",150,95,true],"medium":["https:\/\/geoconversation.org\/wp-content\/uploads\/2026\/06\/otrazhenie-volny-ot-yadra-sdvih-yaponii-300x190.webp",300,190,true],"medium_large":["https:\/\/geoconversation.org\/wp-content\/uploads\/2026\/06\/otrazhenie-volny-ot-yadra-sdvih-yaponii-768x486.webp",768,486,true],"large":["https:\/\/geoconversation.org\/wp-content\/uploads\/2026\/06\/otrazhenie-volny-ot-yadra-sdvih-yaponii-1024x649.webp",1024,649,true],"1536x1536":["https:\/\/geoconversation.org\/wp-content\/uploads\/2026\/06\/otrazhenie-volny-ot-yadra-sdvih-yaponii.webp",1440,912,false],"2048x2048":["https:\/\/geoconversation.org\/wp-content\/uploads\/2026\/06\/otrazhenie-volny-ot-yadra-sdvih-yaponii.webp",1440,912,false],"bricks_large_16x9":["https:\/\/geoconversation.org\/wp-content\/uploads\/2026\/06\/otrazhenie-volny-ot-yadra-sdvih-yaponii-1200x675.webp",1200,675,true],"bricks_large":["https:\/\/geoconversation.org\/wp-content\/uploads\/2026\/06\/otrazhenie-volny-ot-yadra-sdvih-yaponii-1200x760.webp",1200,760,true],"bricks_large_square":["https:\/\/geoconversation.org\/wp-content\/uploads\/2026\/06\/otrazhenie-volny-ot-yadra-sdvih-yaponii-1200x912.webp",1200,912,true],"bricks_medium":["https:\/\/geoconversation.org\/wp-content\/uploads\/2026\/06\/otrazhenie-volny-ot-yadra-sdvih-yaponii-600x380.webp",600,380,true],"bricks_medium_square":["https:\/\/geoconversation.org\/wp-content\/uploads\/2026\/06\/otrazhenie-volny-ot-yadra-sdvih-yaponii-600x600.webp",600,600,true]},"pbg_author_info":{"display_name":"Yulia Frolova","author_link":"https:\/\/geoconversation.org\/en\/author\/giulia-nikolaevna\/","author_img":false},"pbg_comment_info":" No Comments","pbg_excerpt":"The devastating 2011 earthquake in Japan left scientists with a mystery that took years to solve. About 15 minutes after the initial shock, the entire country shifted slightly eastward. The cause was a seismic wave that traveled to the center of the Earth, reflected off the liquid outer core, and returned to the surface. The&hellip;","_links":{"self":[{"href":"https:\/\/geoconversation.org\/en\/wp-json\/wp\/v2\/news\/65252","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/geoconversation.org\/en\/wp-json\/wp\/v2\/news"}],"about":[{"href":"https:\/\/geoconversation.org\/en\/wp-json\/wp\/v2\/types\/news"}],"author":[{"embeddable":true,"href":"https:\/\/geoconversation.org\/en\/wp-json\/wp\/v2\/users\/12"}],"replies":[{"embeddable":true,"href":"https:\/\/geoconversation.org\/en\/wp-json\/wp\/v2\/comments?post=65252"}],"version-history":[{"count":1,"href":"https:\/\/geoconversation.org\/en\/wp-json\/wp\/v2\/news\/65252\/revisions"}],"predecessor-version":[{"id":65254,"href":"https:\/\/geoconversation.org\/en\/wp-json\/wp\/v2\/news\/65252\/revisions\/65254"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/geoconversation.org\/en\/wp-json\/wp\/v2\/media\/65251"}],"wp:attachment":[{"href":"https:\/\/geoconversation.org\/en\/wp-json\/wp\/v2\/media?parent=65252"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/geoconversation.org\/en\/wp-json\/wp\/v2\/categories?post=65252"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/geoconversation.org\/en\/wp-json\/wp\/v2\/tags?post=65252"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}