What is the precise date of the 1960 Valdivia earthquake?

The precise date of the 1960 Valdivia earthquake was May 22, 1960. It struck southern Chile at about 3:11 p.m. local time, or 19:11 UTC, and is generally identified as the largest earthquake ever recorded by modern instruments.

The earthquake was a megathrust rupture along the boundary where the Nazca Plate dives beneath the South American Plate. It lasted roughly 10 minutes and ruptured an exceptionally long section of the Chilean subduction zone. Its commonly reported moment magnitude is 9.5, although scientific estimates are often expressed as a range of 9.4 to 9.6.

The earthquake generated a destructive Pacific-wide tsunami. Waves struck Chile first, then reached Hawaii, Japan, the Philippines, New Zealand, Australia, and the Aleutian Islands. A common mix-up is confusing the main Valdivia shock with the sequence of Concepción earthquakes that began on May 21. Those earlier events were foreshocks; the named Valdivia earthquake itself occurred on May 22.