1970 Ancash Earthquake

Also called the Great Peruvian earthquake, this magnitude 7.9 earthquake struck off Peru's Pacific coast near Casma and Chimbote on 31 May 1970, where the Nazca plate subducts beneath the South American plate, shaking an area of about 83,000 square kilometers for roughly 45 seconds. The shaking destabilized the northern wall of Mount Huascaran, unleashing a debris avalanche of roughly 80 million cubic meters of rock, mud, snow and glacial ice that raced about 18 kilometers at speeds of 280 to 335 kilometers per hour and completely buried the towns of Yungay and Ranrahirca. The combined earthquake and avalanche killed an estimated 66,794 to 70,000 people, the deadliest natural disaster in Peru's history and the deadliest avalanche ever recorded.