EXPLAINER: How glaciers can burst and send floods downstream

FILE – In this April 11, 2015 file photo, tents are seen set up for climbers on the Khumbu Glacier, with Mount Khumbutse, center, and Khumbu Icefall, right, seen in background, at Everest Base Camp in Nepal. The floods that slammed into two hydroelectric plants and damaged villages in northern India were set off by a break on a Himalayan glacier upstream. Glaciers advance and retreat with cycles of snowfall and melting, and can form glacial lakes behind them. This pattern builds up water, as well as a risk the water will break free and flood areas downstream.