Glacial collapse caused seismic activity, 'catastrophic' Nepal floods

KATHMANDU - A glacial collapse triggered seismic activity and catastrophic downstream impacts in Nepal and Tibet, according to the US Geological Survey (USGS). Initially reported as an earthquake, the seismic event was later identified as a glacial collapse and debris flow, according to the agency. At least 160 people lost their lives due to torrents of water and debris that swept downstream on both sides of the Nepal-Tibet border, with hundreds more reported missing in both regions.

The disaster's cause remained unclear in the hours following the early Wednesday incident. Nepal's Foreign Minister Shishir Khanal suggested that an earthquake may have triggered a landslide, which subsequently blocked a river, causing the water to rush downstream. Other theories proposed included a glacial lake flood, where a fragile debris wall holding back glacier melt collapses, or an ice avalanche.

The USGS reported that a magnitude 5.2 seismic event occurred near the Nepal-China border at 8:37am local time on August 26. However, after additional analysis of nearby seismic stations, long-period seismic waves, and satellite imagery, it was determined that the seismic event was actually a glacial collapse and debris flow, with no earthquake occurring.