{"id":32528,"date":"2019-11-19T07:32:04","date_gmt":"2019-11-19T07:32:04","guid":{"rendered":"https:\/\/blogs.agu.org\/landslideblog\/?p=32528"},"modified":"2019-11-19T13:17:47","modified_gmt":"2019-11-19T13:17:47","slug":"haida-gwaii-earthquake-1","status":"publish","type":"post","link":"https:\/\/blogs.agu.org\/landslideblog\/2019\/11\/19\/haida-gwaii-earthquake-1\/","title":{"rendered":"Landslides triggered by the Mw=7.8 Haida Gwaii earthquake in Canada"},"content":{"rendered":"<h4>Landslides triggered by the Mw=7.8 Haida Gwaii earthquake in Canada<\/h4>\n<p>On 27 October 2012 the <a href=\"https:\/\/en.wikipedia.org\/wiki\/2012_Haida_Gwaii_earthquake\">Mw=7.8 Haida Gwaii earthquake<\/a> struck off the coast in <a href=\"https:\/\/blogs.agu.org\/landslideblog\/?s=British+Columbia&amp;submit.x=0&amp;submit.y=0&amp;mswhere=blog\">British Columbia<\/a> in <a href=\"https:\/\/blogs.agu.org\/landslideblog\/?s=canada&amp;submit.x=0&amp;submit.y=0&amp;mswhere=blog\">Canada<\/a>.\u00a0 This was a shallow earthquake with a dominantly thrust-type mechanism, which would be expected to generate substantial numbers of landslides if it occurred directly under hilly terrain.\u00a0 In this case, a comparatively small area of Haida Gwaii (formerly the Queen Charlotte Islands) was affected by significant shaking.\u00a0 The impacts in terms of landslides are documented in a new paper (<a href=\"https:\/\/link.springer.com\/article\/10.1007\/s10346-019-01292-7\">Barth <em>et al.<\/em> 2019<\/a>) published in the journal <a href=\"https:\/\/link.springer.com\/journal\/10346\"><em>Landslides<\/em><\/a>.\u00a0 This is a particularly interesting case as the study area, which extends over about 1350 km<sup>2<\/sup>, consists of undisturbed, forested hillsides.\u00a0 This is important for two reasons:<\/p>\n<ol>\n<li>It removes the effects of human activity on landslide susceptibility, giving a dataset that is less complex to interpret than has been the case elsewhere;<\/li>\n<li>The contrast between native forest and the bear rock \/ soil of a landslide makes mapping comparatively straightforward using satellite imagery.<\/li>\n<\/ol>\n<p>Thus, this is a key event for understanding the landslide impacts of large earthquakes.<\/p>\n<p>In total <a href=\"https:\/\/link.springer.com\/article\/10.1007\/s10346-019-01292-7\">Barth <em>et al.<\/em> (2019)<\/a> have mapped 244 landslides triggered by the earthquake.\u00a0 The authors provide an example of these landslides in the area of Gowaia Bay in Haida Gwaii:-<\/p>\n<div id=\"attachment_32529\" style=\"width: 650px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-32529\" class=\"size-full wp-image-32529\" src=\"https:\/\/blogs.agu.org\/landslideblog\/files\/2019\/11\/19_11-Canada-1-e1574147062547.jpg\" alt=\"Landslides from the Mw=7.8 Haida Gwaii earthquake\" width=\"640\" height=\"451\" \/><p id=\"caption-attachment-32529\" class=\"wp-caption-text\">Landslides from the Mw=7.8 Haida Gwaii earthquake. Image from <a href=\"https:\/\/link.springer.com\/article\/10.1007\/s10346-019-01292-7\">Barth <em>et al.<\/em> (2019)<\/a>.<\/p><\/div>\n<p>.<\/p>\n<p><a href=\"https:\/\/link.springer.com\/article\/10.1007\/s10346-019-01292-7\">Barth <em>et al.<\/em> (2019)<\/a> have looked at multiple epochs of satellite imagery, and examined the rates at which landslides occur.\u00a0 They find that:<\/p>\n<ul>\n<li>Prior to the earthquake, the average rate was 1.44 new landslides per year per 100 km<sup>2<\/sup> in the study area;<\/li>\n<li>The 244 landslides triggered in the earthquake dramatically increases this to 18.1 new landslides per year per 100 km<sup>2<br \/>\n<\/sup><\/li>\n<li>In the three years after the earthquake the rate of new landslides decreased to 1.93 per year per 100 km<sup>2<br \/>\n<\/sup><\/li>\n<li>And finally, in the period from 2016 to 2018 this reduced to 1.0 new landslides per year per 100 km<sup>2<\/sup>.<\/li>\n<\/ul>\n<p>So, it is clear that the earthquake caused a very dramatic spike in the landslide rate and, as has been established elsewhere, an above average rate continued in the post-seismic period, before settling back down to the background rate.\u00a0 This is a dataset that should allow a more detailed understanding of the control on landslides from different physical parameters, and thus it is an important new dataset in the growing <a href=\"https:\/\/www.sciencebase.gov\/catalog\/item\/586d824ce4b0f5ce109fc9a6\">catalogue of coseismic landslide inventories<\/a>.<\/p>\n<h4>Reference<\/h4>\n<p>Barth, S., Geertsema, M., Bevington, A.R. <em>et al.<\/em> 2019. <a href=\"https:\/\/link.springer.com\/article\/10.1007\/s10346-019-01292-7#citeas\">Landslide response to the 27 October 2012 earthquake (M<sub>W<\/sub> 7.8), southern Haida Gwaii, British Columbia, Canada<\/a>.\u00a0 <em>Landslides<\/em>. <a href=\"https:\/\/doi.org\/10.1007\/s10346-019-01292-7\">https:\/\/doi.org\/10.1007\/s10346-019-01292-7<\/a><\/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>A new study (Barth et al. 2019) has mapped the landslides triggered by the 27 October 2012 Mw=7.8 Haida Gwaii earthquake in British Columbia, Canada<!-- 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":32529,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[537],"tags":[4,16802,23,469,725,192,17],"class_list":["post-32528","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-earthquake-induced-landslide","tag-canada","tag-coseismic-landslide","tag-earthquake","tag-featured","tag-north-america","tag-paper","tag-research"],"_links":{"self":[{"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/posts\/32528","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=32528"}],"version-history":[{"count":0,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/posts\/32528\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/media\/32529"}],"wp:attachment":[{"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/media?parent=32528"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/categories?post=32528"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/tags?post=32528"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}