{"id":17951,"date":"2016-03-08T07:00:18","date_gmt":"2016-03-08T07:00:18","guid":{"rendered":"http:\/\/blogs.agu.org\/landslideblog\/?p=17951"},"modified":"2016-03-08T03:45:34","modified_gmt":"2016-03-08T03:45:34","slug":"kalimpong-day-4-part-1","status":"publish","type":"post","link":"https:\/\/blogs.agu.org\/landslideblog\/2016\/03\/08\/kalimpong-day-4-part-1\/","title":{"rendered":"Kalimpong Day 4 part 1: An interesting and deadly roadside landslide"},"content":{"rendered":"
Kalimpong Day 4 part 1: An interesting and deadly roadside landslide<\/h5>\n

On Kalimpong Day 4, part of our UKIERI<\/a> supported trip to the town of Kalimpong, I spent the morning with Major Joshi and colleagues from the Border Roads Organisation<\/a> looking at a landslide on State Highway 31A, the road to Gangtok.\u00a0 This is a valley floor road, located on the banks of the Teesta River.\u00a0 Earlier this year there was a significant landslide on this road that killed two people and injured several others.\u00a0 Save the Hills covered this landslide in detail at the time<\/a> – this is one of the images from their post.\u00a0 Note the truck precariously balanced close to the edge of the road.<\/p>\n

\"Kalmipong

Image of the fatal landslide on State Highway 31A in January 2016. Courtesy of Save the Hills<\/a><\/p><\/div>\n

.<\/p>\n

The road is now clear but remains dangerous.\u00a0 This is an image of the site as of the time of my visit:<\/p>\n

\"Kalimpong

Kalimpong Day 4: The SH31A slope on the Teesta River<\/p><\/div>\n

.<\/p>\n

The source of the January 2016 landslide is located above the white 4×4.\u00a0 Beyond that is another unstable and obviously deformed mass that is waiting to fail.\u00a0 The risk to road users is very clear.\u00a0 This is a classic rock joint controlled instability; this image shows the joint pattern in the unstable rock mass:<\/p>\n

\"Kalimpong

Kalimpong Day 4: Joints in the slope on State Highway 31A<\/p><\/div>\n

.<\/p>\n

There are two major joint sets visible, both steeply inclined.\u00a0 On the image one is diagonal from top right to bottom left, and the other top left to bottom right.\u00a0 These provide the surface to allow a wedge failure.\u00a0 The release surface is the foliation that forms the schistosity, which creates a surface that runs parallel to the road but dips steeply into the slope.\u00a0 This is best seen just to the left of the centre of the image, three quarters of the way up the slop.\u00a0 Here the two steeply dipping joints and the foliation have formed a classic wedge failure from which a block has detached,\u00a0 Once you have your eye in yo can see that these features occur all over the slope.<\/p>\n

A little further along the slope this joint pattern changes, such that the instability in the slope is greatly reduced:<\/p>\n

 <\/p>\n

\"Kalimpong

Kalimpong Day 4: Lower levels of instability with a more advantageous joint set<\/p><\/div>\n

.<\/p>\n

These do not look like large failures, and indeed they are not, but the force that they can exert is remarkable.\u00a0 This is the remains of an excavator that was caught in the January 2016 landslide.\u00a0 Note the damage to the boom and to the cab.\u00a0 The driver escaped:<\/p>\n

\"Kalimpong

Kalimpong Day 4: Damage to an excavator associated with a landslide in January 2016<\/p><\/div>\n

.<\/p>\n

As the SW monsoon approaches, this slope is extremely hazardous.\u00a0 For non-technical reasons it does not seem possible to blast this rock mass to reduce the hazard, so the only option is to monitor it and close the road when instability is noted.\u00a0 This is not a trivial task.\u00a0 I suspect we will hear more about this slope in the months ahead.<\/p>\n","protected":false},"excerpt":{"rendered":"

Kalimpong Day 4: an interesting and hard to manage rockslide that killed two people on State High 31A in India in January 2016<\/p>\n","protected":false},"author":22,"featured_media":17953,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":"","_members_access_role":[],"_members_access_error":""},"categories":[3],"tags":[469,5,959,136,72],"class_list":["post-17951","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-landslide-report","tag-featured","tag-india","tag-landslide-report","tag-rockslide","tag-south-asia"],"_links":{"self":[{"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/posts\/17951","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=17951"}],"version-history":[{"count":0,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/posts\/17951\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/media\/17953"}],"wp:attachment":[{"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/media?parent=17951"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/categories?post=17951"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs.agu.org\/landslideblog\/wp-json\/wp\/v2\/tags?post=17951"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}