Landslide: Chamoli, Uttarakhand, India,

 

    The above satellite image of the Himalayan mountains was taken at the origin and path of a landslide that devastated Chamoli, India on Feb. 7, 2021. The origin of the landslide is located in the bottom right portion of the image, while its path (represented by the yellow-dotted line) meanders from the bottom right to top left portion of the image. The destructiveness of this event was exacerbated by heavy water flow due to natural causes (e.g., glacial melt and heavy rains) as well as the presence of hydroelectric plants (e.g., Tapovan Hydroelectric Plant--located in the upper left portion of the image).

    It was initially thought that the landslide was caused by the collapse of a glacier, resulting in a glacier outburst flood. However, scientists led by Dr. Dan Shugar used seismic measurements to determine when the landslide began and subsequently were able to locate satellite images of the location mere hours after the landslide occurred, including one taken 10 minutes after the beginning of the landslide and another 27 minutes later. Using these images, in conjunction with eyewitness reports and video as well as other remote sensing data, Shugar and colleagues determined that the actual cause of the landslide was a massive rockfall (one of the largest ever recorded) at Ronti Peak. The devastation of the rockfall was exacerbated by large amounts of glacial meltwater, recent heavy rainfall, and water released from hydroelectric dams in the path of the landslide, which increased the speed and mobility of the landslide as it moved down the mountain. Unfortunately, those in the path of this landslide had little warning, but Shugar and colleagues found evidence of instability at Ronti Peak dating back to at least 2016, suggesting that remote sensing can allow for the establishment of early warning systems in the Himalayas and other landslide-prone areas.

Relevant Links:

https://www.planet.com/pulse/rapid-response-research-the-chamoli-landslide/

https://science.sciencemag.org/content/early/2021/06/09/science.abh4455