{"id":13365,"date":"2014-11-11T11:46:13","date_gmt":"2014-11-11T11:46:13","guid":{"rendered":"http:\/\/blogs.agu.org\/landslideblog\/?p=13365"},"modified":"2014-11-11T11:46:13","modified_gmt":"2014-11-11T11:46:13","slug":"the-donghekou-landslide-in-china","status":"publish","type":"post","link":"https:\/\/blogs.agu.org\/landslideblog\/2014\/11\/11\/the-donghekou-landslide-in-china\/","title":{"rendered":"Review of a paper: The Donghekou landslide in China"},"content":{"rendered":"
The Donghekou landslide<\/h5>\n

One of the largest landslides triggered in the remarkable 2008 Wenchuan earthquake in China<\/a> occurred at Donghekou<\/a> in Qingchuan County.\u00a0 This was a large slide – it has a volume of about 100 million cubic metres and it traveled over a distance of about 2 km.\u00a0 Four villages were buried, resulting in about 780 deaths.\u00a0 This landslide has been examined in detail in a paper, Wang et al.<\/em> (2014) just published in Engineering Geology<\/em>.\u00a0 This pair of images, whose provenance is somewhat unclear but which was reproduced in another paper on this landslide (Zhou et al.<\/em> 2013) provides a before and after view of the landslide site:<\/p>\n

\"Donghekou<\/a>

Zhou et al. (2013)<\/p><\/div>\n

.<\/p>\n

The paper is interesting in a number of ways.\u00a0 First, it notes that the slope was known to be unstable and indeed that during heavy rainfall events the local population was frequently evacuated.\u00a0 Of course this was not possible when the earthquake struck.\u00a0 Second, the paper notes that the landslide had a very long runout distance over a near horizontal surface, which suggests very high rates of movement.\u00a0 Using experimental data, the authors conclude that the landslide had such a long runout because of liquefaction of the valley fill deposits during the earthquake, which provided a very low friction surface.\u00a0 The landslide itself was retrogressive in nature, which is unsurprising for such a large slide.<\/p>\n

Perhaps the most interesting aspect of the landslide though is that about six months after the earthquake fumaroles appeared on the landslide mass, generating high temperature gas and a sulfurous odour.\u00a0 These fumaroles are still active, although less so now than in the early phases.\u00a0 Unsurprisingly there has been considerable speculation as to what these fumaroles represent.\u00a0 The authors both sampled the gases emanating from the fumaroles and\u00a0 measured the temperatures a metre into the vent.\u00a0 They found that the ground temperatures were in the range of 50 to 60 degrees Centigrade and that the gases were primarily carbon dioxide and methane, with fluid emissions being rich in potassium, sodium, magnesium and some other trace elements,\u00a0 From this they concluded that the cause of the fumaroles was oxidation of carbonaceous siliceous shale that had been exposed to the air and oxygen-rich water as a result of the movement of the landslide.<\/p>\n

This is of course not without precedent – indeed back in 2008 I wrote a blog post about the strange phenomenon of burning landslides<\/a>, using an example from Dorset in the UK.<\/p>\n

References<\/h5>\n

Zhou,J-W., Cui, P. and Yang, Y.G. (2013). Dynamic process analysis for the initiation and movement of the Donghekou landslide-debris flow triggered by the Wenchuan earthquake.\u00a0 Journal of Asian Earth Sciences<\/em>. 76<\/strong>, 70-84.\u00a0 DOI: 10.1016\/j.jseaes.2013.08.007<\/span><\/p>\n

Wang,G., Huang, R., Louren\u00e7o, S.D.N. and Kamai, T. 2014. . A large landslide triggered by the 2008 Wenchuan (M8.0) earthquake in Donghekou area: Phenomena and mechanisms. Engineering Geology<\/em>.\u00a0 DOI: 10.1016\/j.enggeo.2014.07.013<\/span><\/p>\n

 <\/p>\n

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

A recent paper in Engineering Geology discusses the mechanisms of the Donghekou landslide in China, which killed over 700 people. A strange aspect of the landslide was the formation of fumeroles on the landslide deposit; these are believed to have been the result of oxidation of shales exposed by the landslide<\/p>\n","protected":false},"author":22,"featured_media":13366,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[544],"tags":[16,23,469,184,788],"class_list":["post-13365","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-review-of-a-paper","tag-china","tag-earthquake","tag-featured","tag-review","tag-review-of-a-paper-2"],"_links":{"self":[{"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/posts\/13365","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=13365"}],"version-history":[{"count":0,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/posts\/13365\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/media\/13366"}],"wp:attachment":[{"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/media?parent=13365"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/categories?post=13365"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/tags?post=13365"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}