Analysis of the 23 June 2001 Southern Peru Earthquake Using Locally Recorded Seismic Data

The 23 June 2001, Mw=8.4 southern Peru earthquake ruptured the northern and central part of the previous large earthquake occurred on 13 August 1868, Mw ~9. A detailed analysis of the aftershock sequence was possible due to the deployment of a temporary seismic network along the coast in the Arequipa and Moquegua districts, complementing the Peruvian permanent stations. The deployed temporary network included 10 short period three component stations from the U. of Chile-IRD-France and 7 broad-band seismic stations from the Instituto Geofísico del Perú. This network operated during the first weeks after the mainshock and recorded the major aftershocks like the larger one occurred on 7 July 2001, Mw=7.5, this event defines the southern limit of the rupture area of the 2001 Peruvian earthquake. The majority of the aftershocks shows a thrusting fault focal mechanisms according with the average convergence direction of the subducting Nazca plate, however, normal faulting events are also present in the aftershock sequence like the 5 July 2001, Mw=6.6 one. The depth distribution of the events permitted a detailed definition of the Wadati-Benioff zone in the region. The segment between Ilo and Tacna did not participated in the rupture process of the 2001 southern Peru earthquake. Seismicity located near the political Peruvian-Chilean boundary was reliable determined using the data recorded by the northern Chile permanent network. Analysis of the mainshock and aftershock acelerograms recorded in Arica, northern Chile are also included. The occurrence of the 1995 Antofagasta (Mw=8.0) and the 2001 southern Peru earthquakes suggests that the probability of having a major earthquake in the northern Chile region increased, considering that the previous large earthquake in this region happened in 1877 (Mw ~9), and since that time no earthquake with magnitude Mw>8 had occurred inside of the 1877 estimated rupture area (between Arica and Antofagasta).