1960 Valdivia earthquake

22 May 1960, 19:11 UTC: the largest recorded earthquake

At 19:11:20 UTC on 22 May 1960, a magnitude 9.5 megathrust earthquake struck southern Chile, rupturing roughly 1,000 kilometres of the boundary where the Nazca Plate descends beneath the South American Plate. The USGS catalogs it as the largest instrumentally recorded earthquake — by moment magnitude, not literally '9.5 on the Richter scale.'

The sequence had announced itself: four foreshocks larger than magnitude 7, including a 7.9 shock on 21 May that had already severely damaged the Concepción area and put residents on alert.

In Queule, survivor Jovita Riquelme was attending Mass with her five-year-old daughter when the shaking began; the family later sought high ground.

The sea follows the shaking

Large local tsunamis struck the Chilean coast. Puerto Saavedra was completely destroyed, with waves reaching about 11.5 metres and house remains carried as far as 3 kilometres inland. The land itself moved: coastal areas subsided by roughly 1 to 1.5 metres in places while Isla Guafo rose by as much as 3 metres.

The tsunami then radiated across the Pacific, later killing people and causing major damage in Hawaii — 61 deaths — Japan and the Philippines. Those trans-Pacific deaths came hours later or the following day; the waves reached Japan about a day after the earthquake.

Counting the toll honestly

Fatality estimates differ substantially. The current USGS event page gives approximately 1,655 deaths in total including those outside Chile, and calls earlier reports as high as 5,700 greatly overestimated; about 3,000 people were injured and roughly 2,000,000 left homeless.

One more correction to the old telling: the USGS preferred ShakeMap assigns a maximum Modified Mercalli intensity of IX — not the XII the article's title claimed. By nightfall, southern Chile faced collapsed structures, landslides, altered ground levels and coastal destruction, with the tsunami already crossing the Pacific.