{"id":2554,"date":"2011-01-26T08:18:52","date_gmt":"2011-01-26T08:18:52","guid":{"rendered":"http:\/\/blogs.agu.org\/landslideblog\/?p=2554"},"modified":"2011-01-26T09:53:04","modified_gmt":"2011-01-26T09:53:04","slug":"before-and-after-high-resolution-images-of-the-brazil-landslides","status":"publish","type":"post","link":"https:\/\/blogs.agu.org\/landslideblog\/2011\/01\/26\/before-and-after-high-resolution-images-of-the-brazil-landslides\/","title":{"rendered":"Before and after: high resolution images of the Brazil landslides"},"content":{"rendered":"

Thanks to AAM for pointing this out as a comment in yesterday’s Brazil landslide post<\/a>.\u00a0 The private Geoeye satellite<\/a> has obtained a very high resolution image of the an area affected by the recent landslides in Brazil<\/a>.\u00a0 The image, which was collected\u00a0on 20th January,\u00a0can be viewed and downloaded\u00a0here<\/a>.\u00a0<\/p>\n

The complete image is shown below (obviously compressed here):<\/p>\n

\"\"<\/a><\/p>\n

Satellite image by GeoEye<\/em><\/p>\n

Helpfully, Google Earth also has a Geoeye image of the same area collected in 2008:<\/p>\n

\"\"<\/a><\/p>\n

However, what has happened here becomes much clearer when the image above is draped over the (somewhat rudimentary but still useful) Google Earth terrain model to create a 3D view:<\/p>\n

\"\"<\/a><\/p>\n

There are several interesting elements to this, of which I will highlight a few.\u00a0 I invite others to use the comments to make their own observations.\u00a0<\/p>\n

1.\u00a0\u00a0The area has a mixture of forest and cleared land – and of course we always think that forestry (or lack thereof)\u00a0plays a key role in determining landslide occurrence in heavy rainfall.\u00a0 However, I don’t see much evidence from the above that the woodland has played a key role in determining the landslide locations.\u00a0 Some cleared areas have failed, but so have some wooded areas as well, and vice-versa.\u00a0<\/p>\n

2.\u00a0The key factor in determining landslide location\u00a0seems to be slope gradient, with the landslides notably picking out the steeper slope areas, and in those areas the landslides extend to the ridges.\u00a0<\/p>\n

3. In several\u00a0cases the failures the landslides appear to extend down to bedrock – and indeed the areas with thin soil cover before the landslides are visible in the\u00a0vegetation patterns.\u00a0 In\u00a0some cases it appears that the landslides have preferentially picked out these areas.\u00a0\u00a0<\/p>\n

4. The settlements are very poorly located in terms of risk from these landslides.\u00a0 Note that these are not urban areas, but rural communities.\u00a0 In particular, the area of houses in the centre of the image above has been decimated by the slides that have occurred in the bowl-shaped topography above them.\u00a0 The horror of being in such a location during these landslides is unimaginable.<\/p>\n

5. In the bowl-shaped area above much of the debris appears to have been removed, with two different watercourses being visible (one heading to the east, one to the south, then southwest).\u00a0 It is unsurprising that the watercourses have had so many debris flows.<\/p>\n

Other thoughts and comments?<\/p>\n","protected":false},"excerpt":{"rendered":"

Geoeye has now collected a high quality image of the landslides in Brazil. This post makes some comparisons of this news image and one collected before the event, drawing some provisional conclusions about the landslide occurrence in this area.<\/p>\n","protected":false},"author":22,"featured_media":2555,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":"","_members_access_role":[],"_members_access_error":""},"categories":[1],"tags":[102,469,959,521],"class_list":["post-2554","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-uncategorized","tag-brazil","tag-featured","tag-landslide-report","tag-satellite-image"],"_links":{"self":[{"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/posts\/2554","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=2554"}],"version-history":[{"count":0,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/posts\/2554\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/media\/2555"}],"wp:attachment":[{"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/media?parent=2554"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/categories?post=2554"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/tags?post=2554"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}