{"id":34210,"date":"2020-06-04T05:38:29","date_gmt":"2020-06-04T05:38:29","guid":{"rendered":"https:\/\/blogs.agu.org\/landslideblog\/?p=34210"},"modified":"2020-06-04T15:49:08","modified_gmt":"2020-06-04T15:49:08","slug":"alta-quick-clay-landslide-1","status":"publish","type":"post","link":"https:\/\/blogs.agu.org\/landslideblog\/2020\/06\/04\/alta-quick-clay-landslide-1\/","title":{"rendered":"Alta: a truly remarkable video of a quick clay landslide in Norway"},"content":{"rendered":"<h4>Alta: a truly remarkable video of a quick clay landslide in Norway<\/h4>\n<p>One of the top ten landslide videos of all time was captured yesterday at <span class=\"goog-text-highlight\">Kr\u00e5knes in Alta<\/span>, in the north of Norway. This video shows what is almost certain to be a quick clay landslide.\u00a0 It occurred in the morning of Wednesday 3 June 2020; the video has been <a href=\"https:\/\/www.youtube.com\/watch?v=VWOsGjJo_oI\">posted to Youtube<\/a>. If this video ceases working <a href=\"https:\/\/www.altaposten.no\/lokalt\/nyheter\/2020\/06\/03\/Her-g%C3%A5r-raset-%E2%80%93-Jeg-l%C3%B8p-for-livet-21983422.ece\">then it can also be viewed here<\/a>.<\/p>\n<iframe loading=\"lazy\" title=\"Incredible huge landslide. Houses floating into the sea. (Alta, Norway)\" width=\"800\" height=\"450\" src=\"https:\/\/www.youtube.com\/embed\/VWOsGjJo_oI?feature=oembed\" frameborder=\"0\" allow=\"accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture\" allowfullscreen><\/iframe>\n<p>.<\/p>\n<p><a href=\"https:\/\/www.vg.no\/nyheter\/innenriks\/i\/wP1wEM\/her-gaar-jordraset-i-alta-jeg-loep-for-livet?fbclid=IwAR2WxP8WVI38rwUiV1SD-NW6IJUxRBmEtt62WTiHtlzU9dnUlU340MLI8NA\">VG.no has an article (in Norwegian) that explains the context of the video<\/a>. It was collected by the owner of one of the houses, <span class=\"goog-text-highlight\">Jan Egil Bakkeby<\/span>. He notes that they saw a tension crack downslope from their cabin on Tuesday evening, but chose to stay overnight.\u00a0 It rained on Wednesday morning, after which the landslide occurred. He fled from the house and climbed the hill, and then shot the video.<\/p>\n<p>The landslide appears to have occurred as a coherent raft in the first instance:-<\/p>\n<div id=\"attachment_34215\" style=\"width: 808px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-34215\" class=\" wp-image-34215\" src=\"https:\/\/blogs.agu.org\/landslideblog\/files\/2020\/06\/20_06-Alta-1.jpg\" alt=\"Alta quick clay landslide\" width=\"798\" height=\"462\" srcset=\"https:\/\/blogs.agu.org\/landslideblog\/files\/2020\/06\/20_06-Alta-1.jpg 2067w, https:\/\/blogs.agu.org\/landslideblog\/files\/2020\/06\/20_06-Alta-1-300x174.jpg 300w, https:\/\/blogs.agu.org\/landslideblog\/files\/2020\/06\/20_06-Alta-1-1024x593.jpg 1024w, https:\/\/blogs.agu.org\/landslideblog\/files\/2020\/06\/20_06-Alta-1-768x445.jpg 768w, https:\/\/blogs.agu.org\/landslideblog\/files\/2020\/06\/20_06-Alta-1-1536x889.jpg 1536w, https:\/\/blogs.agu.org\/landslideblog\/files\/2020\/06\/20_06-Alta-1-2048x1186.jpg 2048w\" sizes=\"auto, (max-width: 798px) 100vw, 798px\" \/><p id=\"caption-attachment-34215\" class=\"wp-caption-text\">The initial phases of the Alta quick clay landslide. Still from a <a href=\"https:\/\/www.youtube.com\/watch?v=nK584ol5zNk\">Youtube video<\/a> collected by Jan Egil Bakkeby.<\/p><\/div>\n<p>.<\/p>\n<p>There is a change in gradient of the underlying bedrock towards the sea, which caused the raft to start to fragment in the latter stages:-<\/p>\n<div id=\"attachment_34217\" style=\"width: 809px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-34217\" class=\" wp-image-34217\" src=\"https:\/\/blogs.agu.org\/landslideblog\/files\/2020\/06\/20_06-Alta-2.jpg\" alt=\"Alta quick clay landslide\" width=\"799\" height=\"454\" srcset=\"https:\/\/blogs.agu.org\/landslideblog\/files\/2020\/06\/20_06-Alta-2.jpg 1895w, https:\/\/blogs.agu.org\/landslideblog\/files\/2020\/06\/20_06-Alta-2-300x171.jpg 300w, https:\/\/blogs.agu.org\/landslideblog\/files\/2020\/06\/20_06-Alta-2-1024x582.jpg 1024w, https:\/\/blogs.agu.org\/landslideblog\/files\/2020\/06\/20_06-Alta-2-768x436.jpg 768w, https:\/\/blogs.agu.org\/landslideblog\/files\/2020\/06\/20_06-Alta-2-1536x873.jpg 1536w\" sizes=\"auto, (max-width: 799px) 100vw, 799px\" \/><p id=\"caption-attachment-34217\" class=\"wp-caption-text\">The latter phases of the Alta quick clay landslide. Still from a <a href=\"https:\/\/www.youtube.com\/watch?v=nK584ol5zNk\">Youtube video<\/a> collected by Jan Egil Bakkeby.<\/p><\/div>\n<p>.<\/p>\n<p>There is a great deal of valuable information in the video about the behaviour of the landslide itself, and the way that it generated a displacement wave.<\/p>\n<p>I suspect that this was the second phase of the landslide. The very early shots seem to show considerable existing damage at the front of the slide, on the right side of this screenshot:-<\/p>\n<div id=\"attachment_34219\" style=\"width: 810px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-34219\" class=\" wp-image-34219\" src=\"https:\/\/blogs.agu.org\/landslideblog\/files\/2020\/06\/20_06-Alta-3.jpg\" alt=\"Alta quick clay landslide\" width=\"800\" height=\"453\" srcset=\"https:\/\/blogs.agu.org\/landslideblog\/files\/2020\/06\/20_06-Alta-3.jpg 902w, https:\/\/blogs.agu.org\/landslideblog\/files\/2020\/06\/20_06-Alta-3-300x170.jpg 300w, https:\/\/blogs.agu.org\/landslideblog\/files\/2020\/06\/20_06-Alta-3-768x435.jpg 768w\" sizes=\"auto, (max-width: 800px) 100vw, 800px\" \/><p id=\"caption-attachment-34219\" class=\"wp-caption-text\">The very early phases of the Alta quick clay landslide. Still from a <a href=\"https:\/\/www.youtube.com\/watch?v=nK584ol5zNk\">Youtube video<\/a> collected by Jan Egil Bakkeby.<\/p><\/div>\n<p>.<\/p>\n<p><a href=\"https:\/\/en.wikipedia.org\/wiki\/Quick_clay\">Quick clays<\/a> are glaciomarine materials that have strange properties.\u00a0 When disturbed they are very weak &#8211; indeed their behaviour is similar to that of a fluid.\u00a0 But undisturbed they are much stronger, primarily because of the role of salt, which glues the particle structure together.\u00a0 When this structure is disturbed, the quick clay rapidly weakens, allowing these spectacular landslides to form.<\/p>\n<p>I have featured a number of other quick clay landslides over the years, including examples from <a href=\"https:\/\/blogs.agu.org\/landslideblog\/2019\/11\/14\/lokeburg-1\/\">Sweden<\/a>, <a href=\"https:\/\/blogs.agu.org\/landslideblog\/2016\/11\/13\/asakveien-1\/\">Norway<\/a> and <a href=\"https:\/\/blogs.agu.org\/landslideblog\/2016\/11\/11\/st-luc-de-vincennes-1\/\">Canada<\/a>, and a similar type of landslide from <a href=\"https:\/\/blogs.agu.org\/landslideblog\/2010\/10\/29\/an-amazing-landslide-video-from-manaus-in-brazil\/\">Brazil<\/a>.\u00a0 The most famous example is the <a href=\"https:\/\/blogs.agu.org\/landslideblog\/2010\/11\/04\/the-rissa-landslide-new-old-video-available-online\/\">Rissa landslide, also in Norway, for which another excellent video is available<\/a>.<\/p>\n<p>.<\/p>\n<h4>On reflection 1: Further landslides at Eastchurch in Kent<\/h4>\n<p>Yesterday <a href=\"https:\/\/www.kentonline.co.uk\/sheerness\/news\/firing-range-tremors-cant-help-unstable-cliffs-228220\/\">further failures occurred at Eastchurch in Kent<\/a>, the site of the <a href=\"https:\/\/blogs.agu.org\/landslideblog\/2020\/06\/01\/eastchurch-landslide-1\/\">coastal landslide that destroyed a house over the weekend<\/a>.\u00a0 Further properties are now at risk.<\/p>\n<p>.<\/p>\n<h4>On reflection 2: saving lives at Brumadinho<\/h4>\n<p><a href=\"https:\/\/www.nat-hazards-earth-syst-sci-discuss.net\/nhess-2020-159\/\">An interesting paper is available for online review in the journal NHESS<\/a> looking at ways in which lives could have been saved during the <a href=\"https:\/\/blogs.agu.org\/landslideblog\/2019\/02\/04\/brumadinho-tailings-dam-landslide\/\">Brumadinho tailings dam failure last year<\/a>.<\/p>\n<p>.<\/p>\n<h4>Acknowledgement<\/h4>\n<p>Many thanks to the various people who highlighted this to me via this site, by email and on Twitter. Your help is much appreciated.<\/p>\n<p>&nbsp;<\/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>The remarkable video of a landslide at Alta in Norway yesterday is probably the finest recording of a quick clay landslide to date. <!-- 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":34217,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[29],"tags":[144,469,963,278,88,30048],"class_list":["post-34210","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-landslide-video","tag-europe","tag-featured","tag-landslide-video","tag-norway","tag-quick-clay","tag-quick-clay-landslide"],"_links":{"self":[{"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/posts\/34210","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=34210"}],"version-history":[{"count":0,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/posts\/34210\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/media\/34217"}],"wp:attachment":[{"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/media?parent=34210"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/categories?post=34210"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/tags?post=34210"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}