Geology Explains Destructive Debris Flow

IMAGE: The destroyed Tapovan Vishnugad hydroelectric plant after the devastating debris flow on Feb 7, 2021. CREDIT: Irfan Rashid/Department of Geoinformatics, University of Kashmir

Destruction is a terrible motivator for science, but it does motivate science. Recently, a huge mass wasting event in India destroyed two hydropower facilities and resulted in the deaths of nearly 200 people. Shocking and tragic, scientists raced to understand how and why this event occurred and if it could be prevented in the future.

Over fifty scientists came together to study the landslide, which began when a wedge of rock under a glacier broke off a ridge in the Himalayas. All that rock and ice fell downhill, carrying debris with it, and the damage was extensive. Using a combination of satellite images, eyewitness videos, and seismic data, the team worked to produce computer models of the debris flow.

At first, it was thought that a glacial lake burst through its barrier and flooded the region, but the images revealed no glacier lakes large enough to flood the site. They eventually traced the slide back to a scar that was missing enough rock and ice to cover Washington, D.C. in a half-foot-deep layer. The drop from the ridge was over a mile, and the glacial ice melted as the block fell, causing the resulting flooding that destroyed the power plants.

The real culprit is likely climate change, and the images showed that several other large masses of ice had broken off and fallen in recent years in the same valley, and the…