{"id":34379,"date":"2020-06-18T06:46:57","date_gmt":"2020-06-18T06:46:57","guid":{"rendered":"https:\/\/blogs.agu.org\/landslideblog\/?p=34379"},"modified":"2020-06-18T06:46:57","modified_gmt":"2020-06-18T06:46:57","slug":"rissa-ngi-video","status":"publish","type":"post","link":"https:\/\/blogs.agu.org\/landslideblog\/2020\/06\/18\/rissa-ngi-video\/","title":{"rendered":"Quick clay landslides: an online documentary about Rissa"},"content":{"rendered":"<h4>Quick clay landslides: an online documentary about Rissa<\/h4>\n<p>The recent interest in quick clay landslides, <a href=\"https:\/\/blogs.agu.org\/landslideblog\/2020\/06\/05\/alta-quick-clay-landslide\/\">triggered by the remarkable video from Alta in Norway<\/a>, has led to a number of questions as to the mechanisms of these strange failures.\u00a0 Loyal reader George Haeh kindly pointed out that there is a wonderful video, produced by <a href=\"https:\/\/www.ngi.no\/eng\/\">NGI<\/a>, that seeks to explain the famous 1978 Rissa landslide in Norway.\u00a0 This was the first quick clay landslide to be caught on video; the recording remains a classic.\u00a0 <a href=\"https:\/\/www.youtube.com\/watch?v=3q-qfNlEP4A\">The NGI documentary has been posted to Youtube<\/a>.\u00a0 It includes the famous footage of the landslide in action.<\/p>\n<iframe loading=\"lazy\" title=\"The Quick Clay Landslide at Rissa - 1978 (English commentary)\" width=\"600\" height=\"450\" src=\"https:\/\/www.youtube.com\/embed\/3q-qfNlEP4A?feature=oembed\" frameborder=\"0\" allow=\"accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture\" allowfullscreen><\/iframe>\n<p>.<\/p>\n<p>The video is most definitely of its time, complete with haunting music, and it&#8217;s highly instructive in terms of explaining the sequence of events at Rissa, and the underlying processes.\u00a0 I especially recommend the sequence from about 2 minutes 34 seconds into the recording, which seeks to explain the mechanics of quick clays.\u00a0 The sequence includes an initially intact block of quick clay being subjected to a load that exceeds its strength:-<\/p>\n<div id=\"attachment_34386\" style=\"width: 602px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-34386\" class=\"size-full wp-image-34386\" src=\"https:\/\/blogs.agu.org\/landslideblog\/files\/2020\/06\/20_06-Rissa-1.jpg\" alt=\"Rissa landslide video\" width=\"592\" height=\"664\" srcset=\"https:\/\/blogs.agu.org\/landslideblog\/files\/2020\/06\/20_06-Rissa-1.jpg 592w, https:\/\/blogs.agu.org\/landslideblog\/files\/2020\/06\/20_06-Rissa-1-267x300.jpg 267w\" sizes=\"auto, (max-width: 592px) 100vw, 592px\" \/><p id=\"caption-attachment-34386\" class=\"wp-caption-text\">An intact block of quick clay being loaded to beyond its strength. <a href=\"https:\/\/www.youtube.com\/watch?v=3q-qfNlEP4A\">Still from a video from NGI, posted to Youtube<\/a>.<\/p><\/div>\n<p>.<\/p>\n<p>During failure the video shows the rapid change in the properties of the clay:-<\/p>\n<div id=\"attachment_34389\" style=\"width: 600px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-34389\" class=\" wp-image-34389\" src=\"https:\/\/blogs.agu.org\/landslideblog\/files\/2020\/06\/20_06-Rissa-2.jpg\" alt=\"Rissa landslide video\" width=\"590\" height=\"493\" srcset=\"https:\/\/blogs.agu.org\/landslideblog\/files\/2020\/06\/20_06-Rissa-2.jpg 699w, https:\/\/blogs.agu.org\/landslideblog\/files\/2020\/06\/20_06-Rissa-2-300x251.jpg 300w\" sizes=\"auto, (max-width: 590px) 100vw, 590px\" \/><p id=\"caption-attachment-34389\" class=\"wp-caption-text\">Failure of the block of quick clay being loaded to beyond its strength. <a href=\"https:\/\/www.youtube.com\/watch?v=3q-qfNlEP4A\">Still from a video from NGI, posted to Youtube<\/a>.<\/p><\/div>\n<p>.<\/p>\n<p>The video then goes on to show that remoulding the clay, without adding any fluid, leads to a complete change in the material properties, that now behave as a liquid:-<\/p>\n<div id=\"attachment_34388\" style=\"width: 601px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-34388\" class=\" wp-image-34388\" src=\"https:\/\/blogs.agu.org\/landslideblog\/files\/2020\/06\/20_06-Rissa-3.jpg\" alt=\"Rissa landslide video\" width=\"591\" height=\"500\" srcset=\"https:\/\/blogs.agu.org\/landslideblog\/files\/2020\/06\/20_06-Rissa-3.jpg 809w, https:\/\/blogs.agu.org\/landslideblog\/files\/2020\/06\/20_06-Rissa-3-300x254.jpg 300w, https:\/\/blogs.agu.org\/landslideblog\/files\/2020\/06\/20_06-Rissa-3-768x650.jpg 768w\" sizes=\"auto, (max-width: 591px) 100vw, 591px\" \/><p id=\"caption-attachment-34388\" class=\"wp-caption-text\">Remoulded behaviour of the block of quick clay being loaded to beyond its strength. <a href=\"https:\/\/www.youtube.com\/watch?v=3q-qfNlEP4A\">Still from a video from NGI, posted to Youtube<\/a>.<\/p><\/div>\n<p>.<\/p>\n<p>Perhaps the most interesting part of the video is the response to the addition of a small amount of table salt.\u00a0 The quick clay quickly regains much of its strength, to the extent that the technician can stand a knife up in the material:-<\/p>\n<div id=\"attachment_34390\" style=\"width: 604px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-34390\" class=\" wp-image-34390\" src=\"https:\/\/blogs.agu.org\/landslideblog\/files\/2020\/06\/20_06-Rissa-4.jpg\" alt=\"Rissa landslide video\" width=\"594\" height=\"531\" srcset=\"https:\/\/blogs.agu.org\/landslideblog\/files\/2020\/06\/20_06-Rissa-4.jpg 706w, https:\/\/blogs.agu.org\/landslideblog\/files\/2020\/06\/20_06-Rissa-4-300x268.jpg 300w\" sizes=\"auto, (max-width: 594px) 100vw, 594px\" \/><p id=\"caption-attachment-34390\" class=\"wp-caption-text\">Regain of strength of the quick clay after the addition of a small amount of table salt. Still from a <a href=\"https:\/\/www.youtube.com\/watch?v=3q-qfNlEP4A\">video from NGI, posted to Youtube<\/a>.<\/p><\/div>\n<p>.<\/p>\n<p>I have not seen such a clear explanation of the mechanics of quick clays.<\/p>\n<p>.<\/p>\n<h4>On reflection 1: A valley blocking landslide in Sichuan<\/h4>\n<p><a href=\"https:\/\/news.cgtn.com\/news\/2020-06-17\/Two-missing-after-landslide-hit-SW-China-s-Danba-County-Rp5w16ari8\/index.html\">A large valley blocking landslide in Danba County in Sichuan, China has caused extensive flooding<\/a>. 20,000 people have been evacuated.<\/p>\n<p>.<\/p>\n<h4>On reflection 2: A mudslide-induced house collapse in Nigeria<\/h4>\n<p><a href=\"http:\/\/saharareporters.com\/2020\/06\/17\/two-children-killed-building-collapses-lagos\">Two children have been tragically killed by a mudslide-induced house collapse in Lagos, Nigeria.\u00a0<\/a><\/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>Quick clay landslides: a documentary film made by NGI, posted to Youtube about the Rissa landslide, illustrates the strange properties of quick clays .<!-- 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":34389,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[29],"tags":[650,963,278,88],"class_list":["post-34379","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-landslide-video","tag-feature","tag-landslide-video","tag-norway","tag-quick-clay"],"_links":{"self":[{"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/posts\/34379","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=34379"}],"version-history":[{"count":0,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/posts\/34379\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/media\/34389"}],"wp:attachment":[{"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/media?parent=34379"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/categories?post=34379"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/tags?post=34379"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}