{"id":25242,"date":"2017-08-21T23:59:19","date_gmt":"2017-08-21T23:59:19","guid":{"rendered":"http:\/\/blogs.agu.org\/landslideblog\/?p=25242"},"modified":"2017-08-21T23:59:19","modified_gmt":"2017-08-21T23:59:19","slug":"regent-landslide-2","status":"publish","type":"post","link":"https:\/\/blogs.agu.org\/landslideblog\/2017\/08\/21\/regent-landslide-2\/","title":{"rendered":"Regent landslide in Sierra Leone: the causes of the disaster"},"content":{"rendered":"

Regent landslide in Sierra Leone: the causes of the disaster<\/h4>\n

The latest tally of losses from the Regent landslide<\/a> in Sierra Leone has been released by the coroner<\/a>.\u00a0 To date 499 bodies have been recovered, with about 600 people still reported missing.\u00a0 As expected, this is now the worst landslide of the calendar year to date.<\/p>\n

It is increasingly clear that this disaster was caused by a large, but not huge, failure on the bedrock – regolith interface on a slope above the town<\/a>.\u00a0 This event would undoubtedly have caused mass fatalities, but the true magnitude of the disaster was the result of this failure transitioning to become a high mobility channelised debris flow.\u00a0 This image, from Ultimate FM online<\/a>, is the most revealing:<\/p>\n

\"Regent

The track of the Regent landslide in Sierra Leone, via Ultimate FM online.<\/a><\/p><\/div>\n

.<\/p>\n

Note the broad landslide track heading downstream from the camera.\u00a0 Given that victims from this disaster have been recovered from the sea, it is likely that this landslide travelled about 6.5 km as the crow flies, probably transitioning into a mudflow en route.\u00a0 The slope that failed is about 300 m long and about 130 m from toe to crest.\u00a0 This is a March 2017 Google Earth image of the slope that failed in the Regent landslide disaster:-<\/p>\n

\"Regent

March 2017 Google Earth imagery of the slope that failed in the Regent landslide disaster.<\/p><\/div>\n

.<\/p>\n

Whilst this slope does show signs of some distress, it is highly unlikely that it could have been identified as being dangerous to this degree from visual imagery alone.\u00a0 Identifying potentially hazardous slopes in such settings remains a major challenge.\u00a0 Of greater interest perhaps is to compare the above image with the first high resolution image available in the Google Earth archive:-<\/p>\n

\"Regent

Google Earth imagery from 2005 showing the location of the Regent landslide.<\/p><\/div>\n

.<\/p>\n

The slope has lost some forestry, but the scale of deforestation here is not huge.\u00a0 What is more notable is the change in land use at the toe of the slope.\u00a0 In 2005 this area was mostly unpopulated; immediately prior to the Regent landslide it had dozens of houses.\u00a0 Needless to say it is this growth of urban areas in unsuitable sites that is driving an increase in losses from these events.\u00a0 The combination of this effect with increased rainfall intensities as the climate warms is lethal.<\/p>\n","protected":false},"excerpt":{"rendered":"

New images show that the Regent landslide in Sierra Leone was large translational slide that morphed into a channelised debris flow.<\/p>\n","protected":false},"author":22,"featured_media":25244,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3],"tags":[85,123,469,959,7413,120],"class_list":["post-25242","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-landslide-report","tag-africa","tag-city","tag-featured","tag-landslide-report","tag-sierra-leone","tag-urban"],"_links":{"self":[{"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/posts\/25242","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=25242"}],"version-history":[{"count":0,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/posts\/25242\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/media\/25244"}],"wp:attachment":[{"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/media?parent=25242"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/categories?post=25242"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/tags?post=25242"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}