Which 1960 earthquake in Chile is the strongest instrumentally recorded earthquake ever measured?

The 1960 Valdivia earthquake in Chile is the strongest instrumentally recorded earthquake ever measured. It struck southern Chile on 22 May 1960 with a moment magnitude of 9.5, releasing enormous energy along the boundary where the Nazca Plate moves beneath the South American Plate.

The rupture affected a vast section of the Chilean coast and produced severe ground shaking, landslides, coastal subsidence, and a destructive tsunami. Waves crossed the Pacific Ocean and caused deaths and damage in places including Hawaii, Japan, the Philippines, and New Zealand. The event also triggered volcanic activity in southern Chile.

The earthquake is commonly called the Great Chilean earthquake or the Valdivia earthquake after one of the cities most affected. Its magnitude is based on modern seismological analysis rather than a simple local intensity scale. The 1960 disaster helped demonstrate that earthquakes and tsunamis could have consequences across an entire ocean basin.