1960 Valdivia Earthquake or Great Chilean Earthquake

The 1960 Valdivia earthquake or Great Chilean Earthquake of Sunday, 22 May 1960 is to date the most powerful megathrust earthquake ever recorded on Earth, rating 9.5 on the moment magnitude scale. Megathrust earthquakes generate tsunamis (known as teletsunamis) that can cross entire oceans. The Great Chilean Earthquake occurred in the afternoon (15:11 local time) and its resulting tsunami affected southern Chile, Hawaii, Japan, the Philippines, eastern New Zealand, southeast Australia, and the Aleutian Islands in Alaska.

Image: The 1960 Chilean tsunami radiated outward from a subduction zone along the coast of Chile. Its waves reached Hawaii in 15 hours and Japan in 22 hours.

The epicenter was some 570 km south of Santiago, with Temuco being the closest large city, while Valdivia was the most affected city.

Image: A Valdivia street after the earthquake of 22 May 1960.

The temblor caused localised tsunamis that severely battered the Chilean coast, with waves up to 25 metres.

Image: Aerial view of coastal area on Isla Chiloe, Chile, showing tsunami damage and wave extent. Two hundred deaths were reported here from the tsunami generated just off Chile's coast by the earthquake.

Waves as high as 10.7 metres (35 ft) were recorded 10,000 kilometres from the epicenter, and as far away as Japan and the Philippines. The Chilean tsunami caused death and destruction throughout the Pacific. Hawaii, Samoa, and Easter Island all recorded runups exceeding 4 m.

Image: The picture shows a recording of the Chilean tsunami wave of 22 May, 1960, as it was observed at Acapulco, Mexico, showing vertically the tide height in feet and horizontally time in hours.

The first waves were less than half a metre high but three hours later many oscillations of about 1.5m occurred. With some 20 crests in 10 hours, the waves oscillated quite slowly but regularly. Perturbations of this nature cause large coastal and harbour currents. Compared with a typical tidal oscillation of 2m in 12.4 hours, the tsunami currents could have been 15 times stronger than normal tidal currents.

The source of this earthquake in 1960 extended over a distance of about 1,100 kilometres along the southern Chilean coast. Seismic sea waves excited by the earthquake caused death and destruction in Hawaii, Japan, and the Pacific coast of the United States.

The main tsunami crossed the Pacific Ocean at a speed of several hundred km/h and on May 23, 1960 (about 15 hours after the earthquake) a train of 35-foot waves reached the Hawaiian Islands and crashed into Hilo Bay. Hilo's position in the bay caused a cumulative bounce of tsunami waves far more destructive to Hilo than to other more exposed areas of Hawaii.

The tsunami destroyed or damaged more than 500 homes and businesses downtown and killed 61 people. 282 people were badly hurt. The section of Hilo known as Waiakea was almost completely demolished and had to be cleared after the tsunami. Damage was estimated at $75 million.

Image: The picture shows the epicenter of the earthquake occurred in Chile in 1960.

Image: The picture shows the Hilo map - Area flooded by the 1960 tsunami - Hawaii.

Image: Downtown Hilo, Hawaii, devastated by the tsunami - 1960.

Image: This photo shows damage to property at Waiakea after the tsunami - 1960 Hawaii.

Image: This photo shows damage and debris across from the Hilo Theatre, after the tsunami - 1960 Chile.

Image: 1960 Tsunami - Aftermath of the Chilean tsunami in the Waiakea area of Hilo, Hawaii, 10,000 km from the generation area. Parking meters were bent by the force of the debris-filled waves.

Image: 1960 Tsunami - Damage to Waiakea Buddhist Temple after the 1960 tsunami.

This tsunami caused little damage elsewhere in the Hawaiian Islands, where wave heights were in the 3-17 foot range.

In Japan, the tsunami arrived about 22 hours after the earthquake and 138 people were killed. The tsunami also struck the Philippines, where 32 people were dead or missing.

Image: Waves shown in the photos were recorded by a tide gauge in the Onagawa harbour, Japan. Damaging waves in Onagawa, some of which carried battering rams of floating wood, reached heights of 14 feet. Such waves kept arriving for several hours.

Image: Seen safely from high ground, a wave of the 1960 Chilean tsunami pours into Onagawa.

The death toll and monetary losses arising from such a widespread disaster are not certain. Various estimates of the total number of fatalities from the earthquake and tsunamis have been published, with the USGS citing studies with figures of 2231, 3000, or 5700 killed and another source uses an estimate of 6000 dead. Different sources have estimated the monetary cost ranged from 400 million to 800 million US$ (or 2.9 to 5.8 billion in 2011 dollars, adjusted for inflation).

On 24 May 38 hours after the main shock of the 1960 Valdivia earthquake, Cordon Caulle volcano in Chile began an eruption which ended on 22 July.

Image: 1960 Cordon Caulle volcano in Chile - Eruption.

Each tsunami consists of a succession of waves that arrive from 12 to 20 minutes apart. The 1960 tsunami had eight separate waves that crested between 4 and 14 feet above sea level at the Wailuku River Bridge. The first wave is not necessarily the largest and each wave may crest higher at different locations. Each tsunami may also have its maximum crest at a different location. This fact contributed to many deaths in Hilo in 1960, because people remained in the Waiakea peninsula area, which had minimal damage during the even larger 1946 tsunami.

Image: The 1960 Chile earthquake produced a series of tsunami waves that crossed the Pacific Ocean. This record shows measurements of water levels beneath the Wailuku River Bridge made by seismologist Jerry Eaton and his companions during the first few hours of the tsunami in Hilo, Hawaii.