{"id":28412,"date":"2018-07-26T07:51:33","date_gmt":"2018-07-26T07:51:33","guid":{"rendered":"https:\/\/blogs.agu.org\/landslideblog\/?p=28412"},"modified":"2018-07-26T07:51:33","modified_gmt":"2018-07-26T07:51:33","slug":"fagraskogarfjall-landslide","status":"publish","type":"post","link":"https:\/\/blogs.agu.org\/landslideblog\/2018\/07\/26\/fagraskogarfjall-landslide\/","title":{"rendered":"Detail on the Fagrask\u00f3garfjall landslide from the Icelandic Met Office"},"content":{"rendered":"<h4>Detail on the Fagrask\u00f3garfjall landslide from the Icelandic Met Office<\/h4>\n<p>The <a href=\"http:\/\/en.vedur.is\/\">Icelandic Met Office<\/a> has published two articles online about the <a href=\"https:\/\/blogs.agu.org\/landslideblog\/2018\/07\/24\/fagraskogarfjall-landslide-2\/\">Fagrask\u00f3garfjall landslide in Iceland<\/a>.\u00a0 These provide a lot more detail about the landslide and its timing, and about possible triggering mechanisms.\u00a0 The first, <a href=\"http:\/\/en.vedur.is\/about-imo\/news\/a-large-landslide-falls-in-hitardalur-valley\">published on 10th July<\/a>, indicates that the slide happened at 05:17 am on 7th July, as measured from seismic data.\u00a0 I noted at the time that seismic data might provide insight into the slide; I hope that analysis is possible on the dataset.\u00a0 Interestingly, the report indicates that a smaller landslide may have been noted by a local hunter at about 23:30 the previous evening; this may have been the event that destabilised the main part of the slope.<\/p>\n<p>This report also notes that the debris is up to 20 m thick, and the image below gives a better perspective on spreading mechanism of the slide:-<\/p>\n<div id=\"attachment_28417\" style=\"width: 550px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-28417\" class=\"size-full wp-image-28417\" src=\"https:\/\/blogs.agu.org\/landslideblog\/files\/2018\/07\/18_07-fagraskogarfjall-4.jpg\" alt=\"Fagrask\u00f3garfjall landslide\" width=\"540\" height=\"360\" srcset=\"https:\/\/blogs.agu.org\/landslideblog\/files\/2018\/07\/18_07-fagraskogarfjall-4.jpg 540w, https:\/\/blogs.agu.org\/landslideblog\/files\/2018\/07\/18_07-fagraskogarfjall-4-300x200.jpg 300w\" sizes=\"auto, (max-width: 540px) 100vw, 540px\" \/><p id=\"caption-attachment-28417\" class=\"wp-caption-text\">The front of the debris of the Fagrask\u00f3garfjall landslide in Iceland. Image by T\u00f3mas J\u00f3hannesson via the <a href=\"http:\/\/en.vedur.is\/about-imo\/news\/a-large-landslide-falls-in-hitardalur-valley\">Icelandic Met Office<\/a><\/p><\/div>\n<p>.<\/p>\n<p>The way that the debris has bulldozed the turf is quite interesting, suggesting that the landslide debris may have been sliding rather than flowing, at least in the latter stages of movement.\u00a0 The article also notes that the run-out angle is 12-13\u00b0, which is quite a high level of mobility for a landslide of this volume.\u00a0 This probably implies quite high velocity.<\/p>\n<p>The second article, <a href=\"http:\/\/en.vedur.is\/about-imo\/news\/displacements-in-fagraskogarfjall-for-some-time-before-the-landslide-fell\">published this week<\/a>, provides detail from a digital elevation model (DEM) of the landslide.\u00a0 This can be viewed in the following video:-<\/p>\n<iframe loading=\"lazy\" width=\"640\" height=\"360\" src=\"https:\/\/www.youtube.com\/embed\/UoS3KSPWz_Q?feature=oembed\" frameborder=\"0\" allow=\"autoplay; encrypted-media\" allowfullscreen><\/iframe>\n<p>.<\/p>\n<p>This gives an initial volume estimate of about 7 million m\u00b3 (source volume), and about 10 million m\u00b3 for the debris volume (this allows for entrainment of debris along the route and the bulking of the sediment during motion).\u00a0 Importantly, InSAR analysis of the site by <a href=\"https:\/\/uni.hi.is\/vjp1\/\">Vincent Drouin<\/a> at the University of Iceland and the National Land Survey of Iceland suggests that precursory deformation of the landslide mass could be detected from 2015 onwards.\u00a0 This is not unexpected, but it does provide the potential for detecting these events prior to failure.\u00a0 This is an exciting area, and one that needs further development.<\/p>\n<p>Finally, the article notes that it is unlikely that this event was associated with permafrost degradation given the elevation of the slope.\u00a0 <a href=\"https:\/\/blogs.agu.org\/landslideblog\/2018\/07\/09\/fagraskogarfjall-1\/\">As I noted previously<\/a>, Iceland has had exceptionally wet weather this summer (this is the flip side of the drought in northern Europe).\u00a0 It is likely that the heavy rainfall accelerated the creep of this large rock mass through its failure point.<\/p>\n<p>Thanks to <a href=\"https:\/\/blogs.agu.org\/landslideblog\/2018\/07\/09\/fagraskogarfjall-1\/#comment-216056\"><cite class=\"fn\">Harpa Gr\u00edmsd\u00f3ttir<\/cite><\/a> for highlighting these articles.<\/p>\n<!-- AddThis Advanced Settings generic via filter on the_content --><!-- AddThis Share Buttons generic via filter on the_content -->","protected":false},"excerpt":{"rendered":"<p>Two articles on Icelandic Met Office website provide detail on the Fagrask\u00f3garfjall landslide. The slide, which was detected by the seismic network, had a source volume of about 7 million cubic metres and showed quite a high level of mobility<!-- AddThis Advanced Settings generic via filter on wp_trim_excerpt --><!-- AddThis Share Buttons generic via filter on wp_trim_excerpt --><\/p>\n","protected":false},"author":22,"featured_media":28417,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[144,469,109,306],"class_list":["post-28412","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-uncategorized","tag-europe","tag-featured","tag-iceland","tag-rock-avalanche"],"_links":{"self":[{"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/posts\/28412","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=28412"}],"version-history":[{"count":0,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/posts\/28412\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/media\/28417"}],"wp:attachment":[{"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/media?parent=28412"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/categories?post=28412"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/tags?post=28412"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}