Seismic Source of the Earthquake of Camana Peru 2001 (Mw 8.2) from Joint Inversion of Geodetic and Tsunami Data
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Pure and Applied Geophysics
Seismic Source of the Earthquake of Camana Peru 2001 (Mw 8.2) from Joint Inversion of Geodetic and Tsunami Data CE´SAR JIME´NEZ,1
CARLOS CARBONEL,1 and J. C. VILLEGAS-LANZA2
Abstract—On June 23, 2001 at 15:33 local time (20:33 UTC), a strong earthquake of magnitude Mw 8.2 shook the southern region of Peru, causing considerable material damage and the loss of 74 human lives. The epicenter was located in the sea near the city of Atico (Arequipa). As a coseismic effect, a local tsunami was generated, which after 15 min, caused the flood and destruction of the beach resorts of Camana and resulted in the death of 25 people and 62 missing persons. Another coseismic effect was the subsidence of the coastal zones in the source region, evidenced by geodetic observations. We have conducted a joint inversion of tsunami and geodetic data with a fault plane of variable dip to obtain the slip distribution. The main asperity (slip = 12.6 m) was located offshore Camana, this explains the great damage in this city. The seismic moment was calculated in 2:72 1021 Nm and the corresponding moment magnitude was Mw 8.2. The subfaults near the trench have a null slip, therefore there is a high potential for the generation of a tsunamigenic earthquake in the updip of the fault plane near the trench. Keywords: Tsunami numerical modeling, joint inversion, earthquake of Camana.
1. Introduction On June 23, 2001 at 15:33 local time (20:33 UTC), a strong earthquake of magnitude Mw 8.2 shook the southern region of Peru, causing considerable material damage and the loss of 74 human lives. The epicenter (lat ¼ 16:20 , lon ¼ 73:75 ) was located offshore and near the city of Atico (Arequipa), in the northern extreme of the fault plane. However, the greatest destruction occurred in the city of Camana´.
1 Universidad Nacional Mayor de San Marcos, Lima, Peru. E-mail: [email protected] 2 Instituto Geofı´sico del Peru´, Lima, Peru.
Teleseismic body waveforms can resolve temporal and spatial variations of the seismic rupture process along the strike direction. However, the resolution in the depth direction, or along dip, is relatively poor. To overcome this limitation, we have to look another types of data, for example, geodetic data are used, in general, for earthquakes on land, meanwhile tsunami waveforms have been used, in general, for submarine earthquakes (Satake 1993). The idea is that when an earthquake occurs, geodetic data better resolve the slip on the portion of the fault close to the geodetic observation points, whereas tsunami data better resolve the slip on the portion of the fault responsible of the sea deformation. In addition, if an earthquake is very large (Mw 9), geodetic data can be used also offshore with good resolution, as was demonstrated in the 2011 Tohoku earthquake (Ozawa et al. 2011). From a physical point of view, the joint inversion of tsunami and geodetic data provides a better result with respect to that obtained from models that use a single data set (seismic, geodetic or tsunam
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