On May 31 , 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 . 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 . Most of the survivors were in the cemetery and stadium at the time of the earthquake , as these zones were the highest in town
Ancash earthquake
1970 Ancash earthquake
Yungay, Peru