How did a 2,000-foot-wide glacier collapse trigger deadly Nepal floods?

According to scientists, a glacier section around 2,000 feet wide likely broke off near Nepal-Tibet border and plunged nearly 4,000 feet into a valley, resulting in catastrophic flash floods. The falling ice and rock blocked Lhende Khola river and created a powerful surge of water and debris. It recorded a rise of up to nine metres in 30 minutes downstream.