Huascarán

On 31 May 1970, the Ancash earthquake caused a substantial part of the north side of a mountain, Nevado Huascarán, to collapse and an unstable mass of glacial ice about 800 meters across at the top of Nevado Huascarán to fall. This caused a debris avalanche, burying the town of Yungay and killing 20,000 people (400 survived).^[6] More than 50 million cubic meters of debris slid approximately 15 kilometers downhill at an angle of about 14 degrees. Speeds between 340 mph to 620 mph were achieved.^[7] Most of the survivors were in the cemetery and stadium at the time of the earthquake, as these zones were the highest in town.

• https://en.wikipedia.org/wiki/Yungay,_Peru