September 25, 2013 Earthquake: Arequipa, Peru

Reference #13456:

Felt (VI) at Acari and Caraveli; (IV) at Arequipa and Ica; (III) at Chosica, Huancavelica, Lima, San Luis and Santa Maria; (II) at Cusco. Also felt at Chilca, Los Aquijes, Nuevo Imperial, Oropesa, Pisco, San Vicente de Canete, Santiago and Torata. Felt (III) at Arica, Cuya and Iquique; (II) at Pozo Almonte, Putre and Quillagua, Chile. Felt at Cuenca, Ecuador.

Tectonic Summary

Seismotectonics of South America (Nazca Plate Region)

The South American arc extends over 7,000 km, from the Chilean margin triple junction offshore of southern Chile to its intersection with the Panama fracture zone, offshore of the southern coast of Panama in Central America. It marks the plate boundary between the subducting Nazca plate and the South America plate, where the oceanic crust and lithosphere of the Nazca plate begin their descent into the mantle beneath South America. The convergence associated with this subduction process is responsible for the uplift of the Andes Mountains, and for the active volcanic chain present along much of this deformation front. Relative to a fixed South America plate, the Nazca plate moves slightly north of eastwards at a rate varying from approximately 80 mm/yr in the south to approximately 65 mm/yr in the north. Although the rate of subduction varies little along the entire arc, there are complex changes in the geologic processes along the subduction zone that dramatically influence volcanic activity, crustal deformation, earthquake generation and occurrence all along the western edge of South America.

Most of the large earthquakes in South America are constrained to shallow depths of 0 to 70 km resulting from both crustal and interplate deformation. Crustal earthquakes result from deformation and mountain building in the overriding South America plate and generate earthquakes as deep as approximately 50 km. Interplate earthquakes occur due to slip along the dipping interface between the Nazca and the South American plates. Interplate earthquakes in this region are frequent and often large, and occur between the depths of approximately 10 and 60 km. Since 1900, numerous magnitude 8 or larger earthquakes have occurred on this subduction zone interface that were followed by devastating tsunamis, including the 1960 M9.5 earthquake in southern Chile, the largest instrumentally recorded earthquake in the world. Other notable shallow tsunami-generating earthquakes include the 1906 M8.5 earthquake near Esmeraldas, Ecuador, the 1922 M8.5 earthquake near Coquimbo, Chile, the 2001 M8.4 Arequipa, Peru earthquake, the 2007 M8.0 earthquake near Pisco, Peru, and the 2010 M8.8 Maule, Chile earthquake located just north of the 1960 event.

Reference #10749:

A 7.0 magnitude earthquake struck off Peru's southern coast on Wednesday, the U.S. Geological Survey said, and local media reported that some homes had crumbled in a region near the quake. The epicentre of the earthquake, which was 29 miles (46 kilometres) deep, was 29 miles south of the town of Acari in Peru's southern Arequipa region, the USGS said. There were no immediate reports of injuries or deaths, but a local official reported structural damage in the province of Caraveli in Arequipa. Houses have fallen, walls have fallen, especially those made out of adobe," Santiago Neyra, a town mayor in the region, told RPP radio. "But there has been no report of a loss of human life." A local resident of Acari said on RPP radio that a hill had crumbled - blocking a highway. The quake shook buildings in the capital of Lima 313 miles (504 kms) away, Reuters witnesses said.

Reference #14335:

According to INDECI, in Caraveli Province 385 houses damaged, 58 schools damaged