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Strange Sounds<\/a> – February 9, 2022<\/p>\n Scientists have uncovered the source of a mysterious 2021 tsunami that sent waves around the globe. A magnitude 8.2 earthquake was \u201chidden\u201d within a magnitude 7.5 earthquake in 2021, sending a mysterious tsunami around the world.<\/p>\n In August 2021, a magnitude 7.5 earthquake hit near the South Sandwich Islands, creating a tsunami that rippled around the globe. The epicenter was 47 kilometers below the Earth\u2019s surface \u2014 too deep to initiate a tsunami \u2014 and the rupture was nearly 400 kilometers long, which should have generated a much larger earthquake.<\/p>\n Seismologists were puzzled and sought to understand what really happened that day in the remote South Atlantic.<\/strong><\/p>\n A new study revealed the quake wasn\u2019t a single event, but five, a series of sub-quakes spread out over several minutes. The third sub-quake was a shallower, slower magnitude 8.2 quake that hit just 15 kilometers below the surface. That unusual, \u201chidden\u201d earthquake was likely the trigger of the worldwide tsunami.<\/strong><\/p>\n The study was published in the AGU journal\u00a0Geophysical Research Letters<\/a><\/em>,<\/a>\u00a0which publishes short-format, high-impact papers with implications that span the Earth and space sciences.<\/p>\n Because the South Sandwich Islands earthquake was complex, with multiple sub-quakes, its seismic signal was difficult to interpret, according to lead study author Zhe Jia, a seismologist at the California Institute of Technology. The magnitude 8.2 quake was hidden within the tangle of seismic waves, which interfered with each other over the course of the event. The hidden quake\u2019s signal wasn\u2019t clear until Jia filtered the waves using a much longer period, up to 500 seconds. Only then did the 200-second-long quake, which Jia said accounted for over 70% of the energy released during the earthquake, become clear.<\/p>\n \u201cThe third event is special because it was huge, and it was silent,\u201d Jia said. \u201cIn the data we normally look at [for earthquake monitoring], it was almost invisible.\u201d<\/p>\n Predicting hazards for complex earthquakes can be difficult, as the South Sandwich Islands quake demonstrates. The USGS initially reported the magnitude 7.5 quake and only added the 8.2 event the following day, as the surprise tsunami lapped on shores up to 10,000 kilometers away from its point of origin.<\/p>\n \u201cWe need to rethink our way to mitigate earthquake-tsunami hazards. To do that, we need to rapidly and accurately characterize the true size of big earthquakes, as well as their physical processes,\u201d Jia said.<\/p>\n https:\/\/strangesounds.org<\/a><\/p>\n","protected":false},"excerpt":{"rendered":" Strange Sounds – February 9, 2022 Scientists have uncovered the source of a mysterious 2021 tsunami that sent waves around the globe. A magnitude 8.2 earthquake was \u201chidden\u201d within a magnitude 7.5 earthquake in 2021, sending a mysterious tsunami around the world. In August 2021, a magnitude 7.5 earthquake hit near the South Sandwich Islands, … Continue reading Hidden M8.2 earthquake triggers mysterious 2021 global tsunami<\/span><\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2},"jetpack_post_was_ever_published":false},"categories":[17],"tags":[16470,36,38,317,16471,318,16472],"class_list":["post-20666","post","type-post","status-publish","format-standard","hentry","category-black-horse","tag-2021-tsunami","tag-disaster","tag-earthquake","tag-sandwich-islands","tag-south-atlantic","tag-usgs","tag-zhe-jia"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack-related-posts":[],"jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p8fAkI-5nk","_links":{"self":[{"href":"https:\/\/setapartbytruth.org\/wordpress-watchman\/wp-json\/wp\/v2\/posts\/20666","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/setapartbytruth.org\/wordpress-watchman\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/setapartbytruth.org\/wordpress-watchman\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/setapartbytruth.org\/wordpress-watchman\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/setapartbytruth.org\/wordpress-watchman\/wp-json\/wp\/v2\/comments?post=20666"}],"version-history":[{"count":1,"href":"https:\/\/setapartbytruth.org\/wordpress-watchman\/wp-json\/wp\/v2\/posts\/20666\/revisions"}],"predecessor-version":[{"id":20668,"href":"https:\/\/setapartbytruth.org\/wordpress-watchman\/wp-json\/wp\/v2\/posts\/20666\/revisions\/20668"}],"wp:attachment":[{"href":"https:\/\/setapartbytruth.org\/wordpress-watchman\/wp-json\/wp\/v2\/media?parent=20666"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/setapartbytruth.org\/wordpress-watchman\/wp-json\/wp\/v2\/categories?post=20666"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/setapartbytruth.org\/wordpress-watchman\/wp-json\/wp\/v2\/tags?post=20666"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}