{"id":3110,"date":"2011-05-31T07:25:07","date_gmt":"2011-05-31T07:25:07","guid":{"rendered":"http:\/\/blogs.agu.org\/landslideblog\/?p=3110"},"modified":"2011-05-31T07:25:07","modified_gmt":"2011-05-31T07:25:07","slug":"rupture-mechanics-of-the-japan-tohoku-oki-earthquake-and-landslide-problems-in-the-aftermath","status":"publish","type":"post","link":"https:\/\/blogs.agu.org\/landslideblog\/2011\/05\/31\/rupture-mechanics-of-the-japan-tohoku-oki-earthquake-and-landslide-problems-in-the-aftermath\/","title":{"rendered":"Rupture mechanics of the Japan Tohoku-Oki Earthquake, and landslide problems in the aftermath"},"content":{"rendered":"

Two articles have been published this week in Science Express<\/a>, the rapid online version of the journal Science, on the mechanics of the rupture event of the M=9.0 Tohoku-Oki Earthquake in Japan earlier this year.\u00a0 Both shed some light on the reasons why the earthquake was so immensely damaging.\u00a0 In the first, Simons et al.<\/em> (2011)<\/a> (NB link is a pdf, as the two below) have investigated the magnitude of the slip on the fault.\u00a0 The results are startling – in places the fault is thought to have displaced by as much as 50 metres or more.\u00a0 Meanwhile, Sato et al. (2011)<\/a> measured the\u00a0 displacement of the seafloor during the earthquake, using five seafloor reference stations installed some years before the earthquake.\u00a0 Again, the results are surprising in terms of magnitude of displacement, with one of the stations moving 24 metres horizontally and 3 metres vertically.\u00a0 Finally Ide et al.<\/em> (2011)<\/a> examined the rate of slip on the fault.\u00a0 This paper is accompanied by a very nice press release that explains the implications of the results<\/a>.\u00a0 Interestingly, this work suggests a smaller total slip component than Simons et al.<\/em> (2011) (maximum of about 30 metres, which is still very large indeed), but the\u00a0 most interesting aspect is the late stage, very high strain rate, slip event that occurred close the sea floor on the eastern margin of the fault.\u00a0 This is illustrated beautifully by the animation of slip rate<\/a> (unfortunately it is too large for me to embed!).\u00a0 It could well be that it was this very rapid slip event that was responsible for the large tsunami that created such significant damage in eastern Japan.<\/p>\n

Meanwhile, the remains of Typhoon Songda struck the earthquake-affected areas over the last 24 hours, brining heavy rainfall.\u00a0 The first heavy rainfall event after an earthquake is a high risk period for any seismic event in a mountainous area.\u00a0 In Japan this problem is accentuated by the unusual intensity and magnitude of tropical cyclone precipitation.\u00a0 Early news reports suggest that the impact has been quite large, even though in typhoon terms this is a comparatively small event.\u00a0 The Japan Times reports<\/a> at least some flooding, whilst Xinhua (the Chinese state news agency) reports<\/a> extensive flood and landslide damage:<\/p>\n

Heavy rain has flooded the already-devastated Miyagi area of northern Japan, hindering its reconstruction after a massive earthquake and tsunami in March.\u00a0 Torrential rains brought by typhoon Songda across the country caused landslides and floods, leaving at least 13 people dead and many more missing. Roads have been swept away in at least 200 places and some 19 bridges were damaged. Authorities in the Northeast of Tokyo urged more than 400,000 residents to evacuate their homes Friday following the flooding of a river.\u00a0 In some areas in the North, 54mm of rain fell in just 12 hours. Up to 1,000 troops have been supporting rescue missions and strengthening flood protection. Songda were downgraded to a tropical storm in the southwest of Japan late on Sunday, but strong winds and rain continue to batter the north.<\/p><\/blockquote>\n

A Google translation of an article in Japanese at Yomiuri Online<\/a> suggests that there may have been extensive landslide damage (I have tried to turn this into intelligible English):<\/p>\n

In Midorigaoka\u00a0 landslide damage was confirmed in 189 households out of 190 total units, of which 69 houses were completely destroyed.\u00a0 Nearly 1 meter of road subsidence occurred. The city issued an evacuation advisory to 104 households.<\/p><\/blockquote>\n

I am sure that more information will emerge about these impacts over the next few days.\u00a0 The key point may well be the very high vulnerability of this area to a direct hit from a full strength typhoon later in the summer.\u00a0 Such an event would be associated with very high levels of hazard.\u00a0 As an aside, this issue is a key focus of the “When the Shaking Stops<\/a>” research programme at the Institute of Hazard, Risk and Resilience<\/a> at Durham.\u00a0 We post updates on this research on the IHRR blog<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"

Two articles have been published this week in Science Express, the rapid online version of the journal Science, on the mechanics of the rupture event of the M=9.0 Tohoku-Oki Earthquake in Japan earlier this year.\u00a0 Both shed some light on the reasons why the earthquake was so immensely damaging.\u00a0 In the first, Simons et al. (2011) (NB link is a pdf, as the two below) have investigated the magnitude of …<\/p>\n","protected":false},"author":22,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[23,361,959,975],"class_list":["post-3110","post","type-post","status-publish","format-standard","hentry","category-uncategorized","tag-earthquake","tag-japan","tag-landslide-report","tag-typhoon"],"_links":{"self":[{"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/posts\/3110","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/users\/22"}],"replies":[{"embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/comments?post=3110"}],"version-history":[{"count":0,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/posts\/3110\/revisions"}],"wp:attachment":[{"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/media?parent=3110"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/categories?post=3110"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/tags?post=3110"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}