{"id":35805,"date":"2020-12-16T07:32:32","date_gmt":"2020-12-16T07:32:32","guid":{"rendered":"https:\/\/blogs.agu.org\/landslideblog\/?p=35805"},"modified":"2020-12-16T16:11:10","modified_gmt":"2020-12-16T16:11:10","slug":"bute-inlet-landslide","status":"publish","type":"post","link":"https:\/\/blogs.agu.org\/landslideblog\/2020\/12\/16\/bute-inlet-landslide\/","title":{"rendered":"Bute Inlet: a very long runout proglacial landslide in Canada"},"content":{"rendered":"

Bute Inlet: a very long runout proglacial landslide in Canada<\/h4>\n

News has emerged over the last few days of a recent very large landslide close to Bute Inlet in British Columbia in Canada.\u00a0 This is a really big one – I think the runout is in the order of 13 km, based on a back of the envelope calculation from Google Earth.\u00a0 This landslide has been reported as a variety of phenomenon including a glacial lake outburst flood (GLOF) and a tsunami, and as loyal reader Hig points out below there is an element of these in the chain of events.\u00a0 The location is approximately 50.975, -124.609.<\/p>\n

A good starting point is a set of videos posted to Facebook by 49 North Helicopters<\/a>, who I think discovered the landslide.\u00a0 These show the track of the lower part of the landslide, which was confined within the valley below the glacier.\u00a0 You should be able to access them via the embedded tweets below:-<\/p>\n

https:\/\/twitter.com\/GeoBrentatlarge\/status\/1338535716813344768?s=20<\/p>\n

.<\/p>\n

Brent Ward<\/a> from the Department of Earth Sciences at Simon Fraser University<\/a> has been tweeting extensively about this landslide<\/a>, and he has also appeared on the TV News to discuss the slide.\u00a0 His interpretation of the events is I think spot on,\u00a0 <\/a>and my description here is based on this.<\/p>\n

The full extent of the landslide can be seen on the Google Earth image, obviously captured before the failure, below.\u00a0 I have annotated the location of the original landslide, the position of Elliot Lake, the track of the landslide and the location of the outwash deposits:-<\/p>\n

\"Bute

Annotated Google Earth image of the approximate details of the landslide near to Bute Inlet in Canada<\/p><\/div>\n

.<\/p>\n

Planet Labs has imagery from 2 December 2020 that captures the aftermath of the landslide – clearly the event occurred before this date.\u00a0 This is the source area of the landslide and the remains of Elliot Lake:-<\/p>\n

\"Bute

Planet Labs image of the landslide near to Bute Inlet in Canada. Image copyright Planet Labs, used with permission.<\/p><\/div>\n

.<\/p>\n

Note the scale bar in the bottom right corner of the image – this is a very large failure.\u00a0 The interpretation is that a large failure occurred on the rock slope to the west of the front of the glacier.\u00a0 The very large mass entered the lake, driving a huge displacement wave and entraining both the water and lake sediment to form a catastrophic debris flow (or a hypersaturated flow?) down the valley.\u00a0 The track of the flow is captured very nicely in the 49 North Helicopters videos<\/a>.\u00a0 This is a still from one of them:-<\/p>\n

\"Bute

A still from one of the 49 North Helicopters videos<\/a> of the track of the Bute Inlet landslide.<\/p><\/div>\n

.<\/p>\n

At the mouth of the valley there is extensive deposition of sediment:-<\/p>\n

\"Bute

A still from one of the 49 North Helicopters videos<\/a> of the lower part of the Bute Inlet landslide.<\/p><\/div>\n

.<\/p>\n

The flow then travelled westwards down the Southgate River into Bute Inlet, where a large amount of floating timber was observed.<\/p>\n

This is a classic compound hazard chain – landslide, displacement wave, debris flow, debris flood and possibly even a submarine density flow in Bute Inlet<\/a>.<\/p>\n

Detailed analysis of this event may need to wait until the Spring, but good data should be available from the regional seismic network, which should yield data on the timing, volume and velocity of the event.\u00a0 It is very interesting that this large failure occurred very close to the snout of a retreating glacier – there are parallels to the Barry Arm landslide in Alaska<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"

A massive rockslope failure and 13 km long debris flow near to Bute Inlet in British Columbia, Canada in late November<\/p>\n","protected":false},"author":22,"featured_media":35826,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3],"tags":[4,469,619,959,725,1205,35],"class_list":["post-35805","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-landslide-report","tag-canada","tag-featured","tag-glacier","tag-landslide-report","tag-north-america","tag-planet-labs","tag-video"],"_links":{"self":[{"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/posts\/35805","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=35805"}],"version-history":[{"count":0,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/posts\/35805\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/media\/35826"}],"wp:attachment":[{"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/media?parent=35805"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/categories?post=35805"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/tags?post=35805"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}