Due to the large amounts of snow and ice included in the landslide that caused an estimated 66,000-70,000 casualties, it is also considered to be the world's deadliest avalanche.

Cities, towns, villages—and homes, industries, public buildings, schools, electrical generation and distribution systems, water, sanitary and communications facilities—were seriously damaged or were destroyed.

The northern wall of Mount Huascarán was destabilized, causing a rock, ice and snow avalanche and burying the towns of Yungay and Ranrahirca.

The avalanche started as a sliding mass of glacial ice and rock about 910 metres (2,990 ft) wide and 1.6 km (1 mile) long.

[7] The fast-moving mass picked up glacial deposits and by the time it reached Yungay, it is estimated to have consisted of about 80 million m3 of water, mud, rocks and snow.