{"id":248,"date":"2012-10-10T03:40:05","date_gmt":"2012-10-09T18:40:05","guid":{"rendered":"http:\/\/www.eri.u-tokyo.ac.jp\/_html\/en\/?p=248"},"modified":"2016-04-14T17:01:31","modified_gmt":"2016-04-14T08:01:31","slug":"decade-scale-decrease-in-b-value-prior-to-the-m9-class-2011-tohoku-and-2004-sumatra-quakes","status":"publish","type":"post","link":"https:\/\/www.eri.u-tokyo.ac.jp\/en\/research\/248\/","title":{"rendered":"Decade-scale decrease in b value prior to the M9-class 2011 Tohoku and 2004 Sumatra quakes"},"content":{"rendered":"<p style=\"text-align: center\"><strong>Decade-scale decrease in b value prior to the M9-class 2011 Tohoku and 2004 Sumatra quakes<\/strong><\/p>\n<p style=\"text-align: center\">\u00a0K. Z. Nanjo(NIED)<span style=\"font-size: 11px\">,\u00a0<\/span>N. Hirata, K. Obara<span style=\"font-size: 11px\">\u00a0\u00a0<\/span>and K. Kasahara<\/p>\n<p style=\"text-align: center\"><a href=\"http:\/\/www.agu.org\/pubs\/crossref\/pip\/2012GL052997.shtml\" target=\"_blank\">GEOPHYSICAL RESEARCH LETTERS, doi:10.1029\/2012GL052997<\/a><\/p>\n<p style=\"text-align: left\"><strong>Abstarct<\/strong><\/p>\n<p style=\"text-align: left\">The Gutenberg-Richter frequency-magnitude distribution of earthquakes has become well established in seismology. The slope of the relation between frequency and magnitude (<em>b<\/em> value) is typically 1, but it often shows variations around 1. Based on an analysis of seismicity prior to the 2011 Tohoku and 2004 Sumatra earthquakes (both in magnitude (<em>M<\/em>) 9 class), we show that the pronounced decade-scale decrease in<em>b<\/em>value was a common precursor to both mega-quakes around their hypocenters. This is the first report on<em>M<\/em>9-class quakes to confirm a change in<em>b<\/em> value, which has been predicted based on the results of laboratory experiments. We propose that the <em>b<\/em>value is an important indicator of an impending great earthquake, and has great potential in terms of predicting a future large quake off the Pacific coast of Hokkaido, Japan.<\/p>\n<p style=\"text-align: center\">\u00a0<a href=\"http:\/\/www.eri.u-tokyo.ac.jp\/old\/wp-content\/outreach-old\/uploads\/2012\/10\/obara_thesis5_11.gif\"><img loading=\"lazy\" decoding=\"async\" title=\"obara_thesis5_1\" src=\"http:\/\/www.eri.u-tokyo.ac.jp\/old\/wp-content\/outreach-old\/uploads\/2012\/10\/obara_thesis5_11.gif\" alt=\"\" width=\"399\" height=\"298\" \/><\/a> <a href=\"http:\/\/www.eri.u-tokyo.ac.jp\/old\/wp-content\/outreach-old\/uploads\/2012\/10\/obara_thesis5_2.gif\"><img loading=\"lazy\" decoding=\"async\" title=\"obara_thesis5_2\" src=\"http:\/\/www.eri.u-tokyo.ac.jp\/old\/wp-content\/outreach-old\/uploads\/2012\/10\/obara_thesis5_2.gif\" alt=\"\" width=\"374\" height=\"197\" \/><\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Decade-scale decrease in b value prior to the M9-class 2011 Tohoku and 2004 Sumatra quakes \u00a0K. Z. Nanjo(NIED), &hellip; <a href=\"https:\/\/www.eri.u-tokyo.ac.jp\/en\/research\/248\/\" class=\"more-link\">Continue reading<span class=\"screen-reader-text\"> &#8220;Decade-scale decrease in b value prior to the M9-class 2011 Tohoku and 2004 Sumatra quakes&#8221;<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[11],"tags":[],"class_list":["post-248","post","type-post","status-publish","format-standard","hentry","category-research"],"_links":{"self":[{"href":"https:\/\/www.eri.u-tokyo.ac.jp\/en\/wp-json\/wp\/v2\/posts\/248"}],"collection":[{"href":"https:\/\/www.eri.u-tokyo.ac.jp\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.eri.u-tokyo.ac.jp\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.eri.u-tokyo.ac.jp\/en\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.eri.u-tokyo.ac.jp\/en\/wp-json\/wp\/v2\/comments?post=248"}],"version-history":[{"count":1,"href":"https:\/\/www.eri.u-tokyo.ac.jp\/en\/wp-json\/wp\/v2\/posts\/248\/revisions"}],"predecessor-version":[{"id":249,"href":"https:\/\/www.eri.u-tokyo.ac.jp\/en\/wp-json\/wp\/v2\/posts\/248\/revisions\/249"}],"wp:attachment":[{"href":"https:\/\/www.eri.u-tokyo.ac.jp\/en\/wp-json\/wp\/v2\/media?parent=248"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.eri.u-tokyo.ac.jp\/en\/wp-json\/wp\/v2\/categories?post=248"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.eri.u-tokyo.ac.jp\/en\/wp-json\/wp\/v2\/tags?post=248"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}