The Nepal disaster as seen from space

As many of you surely know by now, on the morning of August 26, 2026, a catastrophic flash flood tore through Nepal’s Rasuwa district, causing immense devastation along the Bhote Koshi and Trishuli river valleys.

Although the cause of the event is not 100% sure at the moment, the trigger seems to be a massive glacier collapse high in the Himalayas.

This morning I was curious to see if we could identify the footprint of this disaster in high-resolution satellite imagery so I started downloading some data. As Sentinel-1 data was not available I resorted to Landsat-8/9 data and filtered for days with low cloud cover. Luckily, I was able to found a Landsat pass from yesterday, just a few hours after the landslide. This is the True Color composite which shows modest cloud coverage.

Unfortunately clouds, snow and ice all look similar (white) to the satellite’s visible eye, so let’s try to use a different composite which targets different channels.

In this second Natural Color composite we can see the extent of the landslide due to the glacier collapse, and even recognize some ice far down the valley. I’m not extremely trained in Landsat imagery and glacier topology so I couldn’t really recognize a defined “scar”, but images from previous years (see final section of this post) seems to suggest yesterday’s image shows a melting that is not consistent with the normal seasonal cycle.

Finding an image from before the collapse was not easy due to the constant presence of clouds in this area, but I was able to identify and process one in mid-June. Here is a GIF with a before/after comparison.

Although it’s still to early to attribute such event to Global Warming, we know increasing temperatures have been contributing to destabilising many glaciers worldwide (especially in the Alps).