Glacier Collapse May Have Caused 'Almost Incomprehensible' Nepal Flood

A massive wall of mud, boulders, and debris rushed more than 60 miles down a river in Nepal on August 26. At least 165 people were killed, and nearly 1,500 are still missing. Scientists believe the disaster began when a glacier high in the Himalayan mountains collapsed. The flood shocked even experts who have studied these mountains for decades.

Scientist Alton Byers from the University of Colorado at Boulder called it one of the largest events of its kind in his 30 years of research. He said, 'The force of this thing is just almost incomprehensible.' Communities along the river were completely destroyed. At least 800 of the missing are from other countries, including dozens of Americans.

Researchers think the collapse started near a peak called Langtang Lirung, close to Nepal's border with Tibet. An estimated 13 million cubic yards of ice and rock — or at least 500,000 large dump-truck loads — came crashing down the mountain. As it fell, it picked up more rock, water, and debris. Speeds may have reached over 186 miles per hour at times.

Scientists used satellite images and a seismic reading to figure out what happened. At first, the shaking was thought to be an earthquake, but it turned out to be a 5.2-magnitude landslide and glacier collapse. Water on one river reportedly rose more than 27 feet in just 30 minutes. The glacial material acted like thick cement, strong enough to toss boulders as big as houses.

Researchers around the world are working to understand what caused the disaster. They are studying satellite images and social media videos showing the event. Scientists will also travel to the area by helicopter and on foot to gather more information. They will need permission from China to go upriver into Tibet and will speak with local communities.

Many scientists say warming temperatures in the region may be making disasters like this more likely. Melting permafrost — frozen ground beneath the surface — can weaken mountain slopes. A recent global study found that permafrost is thawing across much of the planet, using over 20 years of data. Byers warned that these events are happening more often and with greater force than scientists expected.