On 22 May 1960, an earthquake and tsunami occurred in Chile, devastating the city of Valdivia. Most studies have placed it at 9.4–9.6 on the moment magnitude scale, making it the strongest earthquake ever recorded, while some studies have placed the magnitude lower than 9.4. It occurred in the afternoon (19:11:14 UTC, 15:11:14 local time), and lasted 10 minutes. The resulting tsunamis affected southern Chile, Hawaii, Japan, the Philippines, eastern New Zealand, southeast Australia, and the Aleutian Islands.
The epicenter of this megathrust earthquake was near Lumaco, approximately 570 kilometres (350 mi) south of Santiago, with Valdivia being the most affected city. The tremor caused localized tsunamis that severely battered the Chilean coast, with waves up to 25 metres (82 ft). The main tsunami traveled across the Pacific Ocean and devastated Hilo, Hawaii, where waves as high as 10.7 metres (35 ft) were recorded over 10,000 kilometres (6,200 mi) from the epicenter.
The death toll and monetary losses arising from this widespread disaster are not certain.
Various estimates of the total number of fatalities from the earthquake and tsunamis have surfaced, ranging between 1,000 and 6,000 killed. Different sources have estimated the monetary cost ranged from US$400 million to $800 million (or US$4.4 billion to $8.7 billion in 2025, adjusted for inflation).
Chile is located along the Pacific Ring of Fire, a known zone of high seismicity. The earthquake was a megathrust earthquake resulting from the release of mechanical stress between the subducting Nazca plate and South American plate on the Peru–Chile Trench, off the coast of southern Chile. Because of its geography, Chile remains one of the most seismically active countries in the world.
The focus of the earthquake was relatively shallow at 33 km (21 mi), considering that earthquakes in northern Chile and Argentina may reach depths of 70 km (43 mi).
A 2019 research paper postulates that the Liquiñe-Ofqui fault had a Mw9.07 strike-slip sub-event along with the Mw9.37 main thrust sub-event which could help account for how the plate boundary event seemingly "overspent" its tectonic budget. In other words, the previous and current more widely accepted explanation for the earthquake involves the Peru-Chile Trench slipping further than its accumulated slip deficit (the amount of slip available for an earthquake) should allow. The alternative explanation, with two faults slipping nearly simultaneously, could help explain the true mechanism of the earthquake.
Subduction zones are known to produce the strongest earthquakes on Earth, as their particular structure allows more stress to build up before energy is released. Geophysicists consider it a matter of time before this earthquake will be surpassed in magnitude by another. The earthquake's rupture zone was ≈ 800 km (500 mi) long, stretching from Arauco (37° S) to below the Chiloé Archipelago (44° S). Rupture velocity, the speed at which a rupture front expands across the surface of the fault, has been estimated as 3.5 km (2.2 mi) per second. The average slip across all 27 Nazca sub-faults was estimated to be 11 m, with 25–30 m of slip 200–500 km south of the epicenter on offshore sub-faults.
While the Valdivia earthquake was extraordinarily large, the 2016 Chiloé earthquake hints that it did not release all the potential slip in that segment of the plate interface.
The 1960 Chilean earthquakes were a sequence of strong earthquakes that affected Chile between 21 May and 6 June 1960, centered in the Cautín, Malleco, Aysén, and Biobío provinces of the country. The first three quakes, all registering in the planet's top 10 by magnitude for 1960, are grouped together as the 1960 Concepción earthquakes. The first of these was the 8.1 Mw Concepción earthquake at 06:02 UTC-4 on 21 May 1960. Its epicenter was near Curanilahue. The second and third Concepción earthquakes occurred the next day at 06:32 UTC-4 (7.1 Mw) and 14:55 UTC-4 (7.8 Mw) on 22 May. These earthquakes formed a southward migrating foreshock sequence to the main Valdivia shock, which occurred just 15 minutes after the third event.
The earthquake interrupted and effectively ended a protest by coal miners from Lota, who were attempting to march to Concepción to demand higher salaries.
The Valdivia earthquake occurred at 15:11 UTC-4 on 22 May, and affected all of Chile between Talca and Chiloé Island, more than 400,000 square kilometres (150,000 sq mi). Coastal villages, such as Toltén, were struck. At Corral, the main port of Valdivia, the water level rose 4 m (13 ft) before it began to recede. At 16:20 UTC-4, a wave of 8 m (26 ft) struck the Chilean coast, mainly between Concepción and Chiloé. Another wave measuring 10 m (33 ft) was reported ten minutes later.
Hundreds of people were already reported dead by the time the tsunami struck. One ship, Canelo, starting at the mouth of the Valdivia River, sank after being moved 1.5 km (0.93 mi) backward and forward in the river; as of 2005, its mast was still visible from the road to Niebla.
Soil subsidence also destroyed buildings, deepened local rivers and created wetlands in such places as the Río Cruces and Chorocomayo, a new aquatic park north of the city. Extensive areas of the city were flooded. The electricity and water systems of Valdivia were completely destroyed. Witnesses reported underground water flowing up through the soil. Despite the heavy rains of 21 May, the city was without a water supply. The river turned brown with sediment from landslides and was full of floating debris, including entire houses. The lack of potable water became a serious problem in one of Chile's rainiest regions.
The earthquake did not strike all the territory with the same strength; measured with the Mercalli scale, tectonically depressed areas suffered heavier damage. The two most affected areas were Valdivia and Puerto Octay, near the northwest corner of Llanquihue Lake. Puerto Octay was the center of a north–south elliptical area in the Central Valley, where the intensity was at the highest outside the Valdivia Basin. East of Puerto Octay, in a hotel in Todos los Santos Lake, stacked dishes were reported to have remained in place. With the exception of poor building sites, the zone of Mercalli scales intensities of VII or more all lay west of the Andes in a strip running from Lota (37° S) southwards. The area of intensities of VII or more did not penetrate into the Central Valley north of Lleulleu Lake (38° S) and south of Castro (42.5° S). Two days after the earthquake Cordón Caulle, a volcanic vent close to Puyehue volcano, erupted. Other volcanoes may also have erupted, but none were recorded because of the lack of communication in Chile at the time. The relatively low death toll in Chile (5,700) is explained in part by the low population density in the region, and by building practices that took into account the area's high geological activity.
Earthquake lights were reported in Purén.
One of the main aftershocks occurred on 6 June in Aysén Province. This magnitude 7.7 earthquake probably occurred along the Liquiñe-Ofqui Fault, meaning that the fault would have moved as a consequence of the 22 May Valdivia earthquake.
Earthquake-induced tsunamis affected southern Chile, Hawaii, Japan, the Philippines, China, eastern New Zealand, southeast Australia, and the Aleutian Islands. Some localized tsunamis severely battered the Chilean coast, with waves up to 25 m (82 ft). The main tsunami crossed the Pacific Ocean at a speed of several hundred km/h and devastated Hilo, Hawaii, killing 61 people. Most of the tsunami-related deaths in Japan occurred in the northeast Sanriku region of Honshu.