Saturday, June 22, 2024

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Active deformation around South Lhonak lake in Sikkim, India


Planet Labs satellite image of the area of South Lhonak lake in Sikkim, India, after the landslide and GLOF.

Dave Petley, a renowned expert in landslide research and management, authors The Landslide Blog.

Image of a landslide partially covered with a transparent sand-colored overlay and the words “The Landslide Blog,” centered, in white

The group of scientists studying landslides has been actively researching the Glacial Lake Outburst Flood (GLOF) that occurred in Sikkim on October 4, 2023. It is believed that the collapse of the moraine dam was caused by instability in the banks of South Lhonak lake, resulting in a displacement wave that breached the dam and caused significant damage.

Bretwood Higman, a devoted reader, has utilized high-resolution satellite images of the area to greatly aid in understanding the events of October 4th. Hig has created an animation showing the changes in the moraine north of South Lhonak lake leading up to the events.


The section of focus is located in the upper left corner of the picture, near the Planet symbol. The visible extent of movement is clearly visible. I have marked this on the Planet Labs image shown below, taken on September 26, 2023.

Planet Labs satellite image of the area of deformation above South Lhonak lake in Sikkim, India, before the landslide and GLOF.

The photo above shows the region above South Lhonak lake in Sikkim, India before the landslide and GLOF (glacial lake outburst flood). It is an image captured by a Planet Labs satellite on September 27th, 2023, and is being used with their permission.

On October 9th, 2023, the image displayed depicts the amount of material that has been eroded due to landslides in this particular region.

Planet Labs satellite image of the area of deformation above South Lhonak lake in Sikkim, India, after the landslide and GLOF.

The picture above South Lhonak lake in Sikkim, India, shows the deformed area caused by a landslide and GLOF. It was taken by a Planet Labs satellite on 9 October 2023 and is protected by copyright. It is used with permission from Planet Labs.

Dan Shugar, a highly impressive individual, has thoroughly examined this region and shared a thought-provoking thread on Twitter.

Dan has a Twitter thread discussing the path of devastation caused by the flood and how it led to additional landslides downstream because the river banks were undercut.

Reading all the posts in the thread is beneficial.

Reference

Planet Lab PB 2023 is a program that aims to improve life on Earth through space technology. It is based in San Francisco, CA and can be accessed through the Planet Application Program Interface at https://www.planet.com/.

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Text © 2023. The authors. CC BY-NC-ND 3.0

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