Tarapaka Earthquake Report (Northern Chile)

Arash Eslami, International Institute of Earthquake Engineering and Seismology

On June 13, 2005 an earthquake with an estimated magnitude of 7.8 occurred at 1515 km North of Santiago, Chile’s capital at 22:44:33.54 (global time). The epicenter of this earthquake was located at 19.9 ºS and 69.13 ºW. (figure 1) Due to the earthquake 8 people were killed, and many severely injured and homeless have been reported up to now. The French news agency reported at least 17 housing units destroyed and power lines were disconnected in the affected region.

 

Regional Earthquake Structure

This earthquake occurred due to the release of stress from underplating of the Nazaka oceanic plate underneath the resulting South American plate. In this region, the Peru-Chile subduction zone has been identified with a 7.8 cm movement rate towards ENE. This process of underplating has caused a few earthquakes, volcanoes and orogenicity in the Andes Mountains. Underplating zones cause the greatest earthquakes on earth. The largest earthquake over the past 100 years was in 1960 in Chile with a magnitude of 9.5 which occurred in the Peru- Chile subduction zone. The 1960 earthquake, with a rupture of about 900 km along Chile’s coast occurred about 2000 km south of the epicenter of the recent June 13, 2005 earthquake. As reported by USGS and HARV the earthquake was shown to have a normal mechanism (figure 2). The focal depth of the earthquake was reported about 111 km by the USGS.

Fig (1)

 

Fig (2)