Nepal's Avalanches Expose Rising Risks of Himalayan Disasters

A large mass of rock and ice fell from a mountain in Nepal.

It hit the valley and turned into a fast, destructive flow of mud, rocks and water.

At first, people thought an earthquake or a glacial lake flood had caused the damage.

Scientists later said the shaking came from the avalanche hitting the ground, and there was no glacial lake in the valley.

These events are hard to predict because many mountain slopes could become unstable.

Monitoring every high mountain valley would be difficult and expensive.

Seismic stations might help detect avalanches and floods more quickly.

Warnings will only save lives if communities trust them and know how to respond.

The disasters also raise questions about where people should build homes and hydropower projects.