Geologists and glacier experts preliminarily believe a massive glacier collapse was a key factor behind devastating flash floods in Nepal on Wednesday. Satellite analysis indicated that a roughly 2,000-foot-wide section of glacier, located at about 17,000 feet, broke away and plunged about 4,000 feet into a valley. The event occurred about 40 miles north of Kathmandu, with ice and water flowing northwest toward the Bhote Koshi River on the Nepal-China border.

Experts said the falling ice released substantial stored energy, breaking into a fast, dangerous mixture of ice, water and rock. Seismic data showed a sudden downslope movement at about 8:40 a.m. local time, followed by signs of floodwater flow. The USGS initially identified a 4.4-magnitude earthquake but later said no earthquake had occurred; it described vibrations from the landslide as equivalent to a 5.2-magnitude seismic event.

Scientists have not confirmed the precise cause, noting that videos show unusually large water volumes that may indicate additional factors. They have not ruled out climate change, as satellite images showed rapidly shrinking snow cover before the event, but say it is too early to establish a direct link. Hundreds remain missing in Nepal and China’s Tibet region, while rescue work is complicated by remote terrain and debris.