{"id":38018,"date":"2021-07-06T07:28:08","date_gmt":"2021-07-06T07:28:08","guid":{"rendered":"https:\/\/blogs.agu.org\/landslideblog\/?p=38018"},"modified":"2021-07-06T07:28:08","modified_gmt":"2021-07-06T07:28:08","slug":"atami-landslide","status":"publish","type":"post","link":"https:\/\/blogs.agu.org\/landslideblog\/2021\/07\/06\/atami-landslide\/","title":{"rendered":"The source zone of the Atami landslide"},"content":{"rendered":"

The source zone of the Atami landslide<\/h4>\n

The recovery efforts at the site of the Atami landslide<\/a> continue.\u00a0 At the time of writing four bodies have been recovered and a further 24 people remain missing<\/a>.\u00a0 This is substantially lower than we feared yesterday.<\/p>\n

Meanwhile, there is now considerable focus on the cause of the landslide.\u00a0 The Japanese newspaper The Asahi Shimbun has a good article suggesting that inadequate drainage in a fill slope at the landslide source may have been a factor<\/a>.\u00a0 The article details a troubled history of the site from 2006, with allegations of unauthorised dumping of industrial materials and an abandoned development project.<\/p>\n

The Google Earth image archive gives some support to the idea that the slope that failed was manmade.\u00a0 This is the most recent image of the source zone:-<\/p>\n

\"Google

Google Earth image of the source zone of the Atami landslide in Japan. This image is dated 23 December 2020.<\/p><\/div>\n

.<\/p>\n

The bend in the road is clearly supported on a filled slope that is benched.\u00a0 This is more clear in the first image in the archive, which is dated 31 January 2011:-<\/p>\n

\"Archive

Archive Google Earth image of the source zone of the Atami landslide in Japan. This image is dated 31 January 2011.<\/p><\/div>\n

.<\/p>\n

This appears to be the period in which active construction\u00a0 had been recently occurring – The Asahi Shimbun story states that<\/a>:<\/p>\n

In February 2011, the owner of a Tokyo-based holding company that included a construction company among group firms, purchased the site. Complying with city government instructions, the site was filled in with the leftover dirt left in the area.<\/em><\/p>\n

Although I must note that “a lawyer for the company owner denied having the area filled in with dirt and soil”.<\/em><\/p>\n

The 2011 image appears to show a slope that has been artificially constructed, with clear terraces.\u00a0 Almost all of this made ground is absent in the drone video<\/a>:-<\/p>\n

\"The

The source area in the aftermath of the Atami landslide in Japan. Still from a video posted to Youtube.<\/a><\/p><\/div>\n

.<\/p>\n

I noted yesterday<\/a> that the failure was surprisingly deep-seated.\u00a0 Perhaps we know the reason now.<\/p>\n

Catastrophic fill slope failures are well documented.\u00a0 For example, I blogged about a large scale failure in fill at Yeager airport in West Virginia in 2015<\/a>.\u00a0 In conditions of high saturation, fill slope failures can transition into the type of violent mudflow that occurred at Atami.<\/p>\n

Of course at this stage I can only speculate on the cause, but the investigation will undoubtedly take a close look at the design, construction and maintenance of that fill slope, and in particular on the compaction of the materials and the presence or absence of appropriate drainage.<\/p>\n

 <\/p>\n","protected":false},"excerpt":{"rendered":"

News reports and archive Google Earth imagery indicate that the Atami landslide might have occurred on manmade slope <\/p>\n","protected":false},"author":22,"featured_media":38023,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[881,469,851,316,361],"class_list":["post-38018","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-uncategorized","tag-east-asia","tag-featured","tag-fill-slope","tag-google-earth","tag-japan"],"_links":{"self":[{"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/posts\/38018","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=38018"}],"version-history":[{"count":0,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/posts\/38018\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/media\/38023"}],"wp:attachment":[{"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/media?parent=38018"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/categories?post=38018"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/tags?post=38018"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}