Tarapaca, Chile Earthquake

First Posting | Summary
Posting Date: June 14, 2005, 2:00:00 PM

A major earthquake struck Chile on Monday, June 13, 2005, at 22:44 UTC. The USGS has estimated the earthquake’s magnitude at 7.8. The epicenter was located about 70 miles east northeast of Iquique, Chile, at an estimated depth of 67 miles. The quake, which lasted for 50 seconds, was the third strongest earthquake in the world since the December M9.0 event in Indonesia. Its depth and location in the sparsely populated Andean region minimized casualties and property damage. Power outages caused by landslides were reported in the nearby port cities of Iquique and Arica. A power outage also halted production at Cerro Colorado, a major copper mining operation in the northern mountain region. At least 8 people were killed in the earthquake and several homes were damaged in villages around the epicenter, but no major damage was reported in the nearest major cities of Arequipa, Peru, and La Paz, Bolivia. The seismicity of northern Chile is dominated by the convergence of the Nazca and South American plates. The Nazca plate is subducting east/northeast beneath the South American plate at the rate of about 78-84 mm/year. The Nazca plate subduction zone just offshore of Chile and Peru is capable of producing very large magnitude interface subduction zone earthquakes as well as deeper, so-called intraslab earthquakes. The historic interface events include the largest earthquake on record—a M9.5 event that occurred in 1960. Other large earthquakes in this region include the 1985 M7.8 Santiago earthquake and the 1995 M8.0 Antofagasta earthquake. Most of these events occurred to the south of the current event, in central and southern Chile. The segment that generated the Monday’s earthquake has not experienced a large interface earthquake in the last 100 years, with no event greater than 8.0 since late the 1800s. Monday’s event was an intraslab earthquake, occurring within the subducting Nazca plate. Although in recent history there have not been great interface earthquakes in this segment of the subduction zone, deep instraslab events such as this one are relatively frequent. There have been at least three such events in the vicinity of this one in the last 100 years with a magnitude greater than 7.0. Using the available information about the parameters of this event, the AIR earthquake team has run the model for Chile. Results indicate that insured losses will not exceed $100 million.

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Posting Date: June 14, 2005, 2:00:00 PM