M 8.4 - 6 km SSW of Atico, Peru

At least 74 people killed, including 26 killed by a tsunami; 2,689 injured; 17,584 homes destroyed (VIII) and 35,601 homes damaged in the Arequipa-Camana-Tacna area. An additional 64 people missing due to the tsunami in the Camana-Chala area. Landslides blocked highways in the epicentral area. Many of the historic buildings at Arequipa were damaged or destroyed. Some people injured and damage reported in the Arica, Chile area. Felt (VII) at Arica, (VI) at Iquique, (V) at Calama and (III) at Tocopilla, Chile. Felt strongly in much of southern Peru and northern Chile. Felt (III) at La Paz, Bolivia.

Acceleration of 0.29g was recorded at Moquegua. Tsunami runup heights near Camana are estimated from field evidence to have reached approximately 7m at some locations; at other locations, the tsunami inundation distance extended more than 1 km inland from the coast. Tsunami wave heights (peak-to-trough) recorded from selected tide stations: 2.5m at Arica; 1.5m at Iquique; 1.0m at Coquimbo, Chile.

The earthquake occurred at the boundary between the Nazca and South American tectonic plates. The two plates are converging towards each other at a rate of about 78mm per year. The earthquake occurred as thrust-faulting on the interface between the two plates, with the South American plate moving up and seaward over the Nazca plate.

Southwestern Peru has a history of very large earthquakes. The June 23 shock originated just southeast of the source of a magnitude 7.7 earthquake that occurred in 1996, and it appears to have involved rupture of part of the plate-boundary segment that produced an earthquake of magnitude approximately 9.0 in 1868. The 1868 earthquake was destructive in towns that were heavily damaged in the June 23 earthquake. The 1868 earthquake produced a tsunami that killed thousands of people along the South American coast and also caused damage in Hawaii and alarm in Japan.

For detailed information about this earthquake, see Terremoto de la Region Sur de Peru del 23 de Junio de 2001, online at http://www.igp.gob.pe/cns/net_main.html.