The 1970 Huascarán Debris Avalanche occurred on May 31 1970, when a debris avalanche and mudflow triggered by the Ancash earthquake destroyed the town of Yungay, Peru and 10 nearby villages, leaving up to 30,000 people dead. It is the deadliest avalanche or glacier-related disaster in history, surpassing the death toll from the previous deadliest avalanche disaster, the avalanches of White Friday on the Italian front of World War I and the third or fourth most deadly landslide-related disaster of the 20th century, after the Haiyuan landslides (China), the Armero tragedy (Colombia) and by some estimates the Khait landslide (Tajikistan).
The north peak of Huascarán from which the avalanche originated had been considered unstable since 1962, when a smaller collapse wiped out several villages of the Callejón de Huaylas valley near Yungay. However, the provincial government made efforts to prevent the news from spreading and urged people not to panic. The 1970 earthquake destabilized a glacier and snowmass which surged rapidly downhill, becoming a mudflow as it accumulated large volumes of loose dirt, rock and surface water. The death toll was made worse due to the earthquake having occurred on a Sunday, as thousands more people had congregated in Yungay for market when the mudflow struck and leveled the city. The slide then entered the Río Santa and caused extensive damage as it flowed all the way downstream to the Pacific Ocean, a distance of 160 kilometres (100 mi), mostly thro
Why this event still matters
Historical incidents shape the rules that protect people today — building codes, evacuation policy, warning systems and inspection regimes almost always trace back to a specific disaster. Studying 1970 Yungay landslide alongside current events is how preparedness improves.
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