TY - JOUR
T1 - Source study and tectonic implications of the historic 1958 Las Melosas crustal earthquake, Chile, compared to earthquake damage
AU - Alvarado, Patricia
AU - Barrientos, Sergio
AU - Saez, Mauro
AU - Astroza, Maximiliano
AU - Beck, Susan
N1 - Funding Information:
The authors would like to acknowledge the NSF grant EAR-0510966, the National PERISHIP Dissertation Award (2004), PICT2006-0122 and UNSJ-CICITCA 21/E814 and the Millenium Nucleous of Seismotectonics and Seismic Hazards. We thank Victor Ramos and an anonymous reviewer for their reviews and suggestions that helped to improve this paper. We thank Rolando Armijo for fruitful discussions. Maps were generated using Generic Mapping Tools ( Wessel and Smith, 1991 ).
PY - 2009/6
Y1 - 2009/6
N2 - The 4 September 1958 earthquake has been the largest event recorded at shallow depths in the western flank of the Andes on Chilean territory. New estimates of fault orientation, depth and size have been carried out using modern techniques of body-wave modeling. Two possible fault planes solutions with right-lateral displacement on an east-west fault or left-lateral displacement on a north-south fault nucleated at 5-9 km depth produce the best fit to teleseismic recordings. A seismic moment M0 of 0.227 × 1019 N m associated with a moment-magnitude Mw of 6.3 has been estimated with these techniques, which is a more reliable estimation of earthquake size than the 0.4-0.7 units larger surface-wave magnitude Ms earlier reported. Although no surface rupture for the 1958 Las Melosas crustal earthquake was reported, the displacement along east-west structures like that one suggested for one of the fault plane in our focal mechanism solution seems to be an efficient mechanism to accommodate differences in shortening from north to south in the High Andean Cordillera. Reports on damage, landslide effects as well as re-analysis of intensities associated with the new seismic source estimations for the 1958 Las Melosas earthquake are presented to further estimate the hazard to which this zone, and others along the western foothills of the Andes, is exposed.
AB - The 4 September 1958 earthquake has been the largest event recorded at shallow depths in the western flank of the Andes on Chilean territory. New estimates of fault orientation, depth and size have been carried out using modern techniques of body-wave modeling. Two possible fault planes solutions with right-lateral displacement on an east-west fault or left-lateral displacement on a north-south fault nucleated at 5-9 km depth produce the best fit to teleseismic recordings. A seismic moment M0 of 0.227 × 1019 N m associated with a moment-magnitude Mw of 6.3 has been estimated with these techniques, which is a more reliable estimation of earthquake size than the 0.4-0.7 units larger surface-wave magnitude Ms earlier reported. Although no surface rupture for the 1958 Las Melosas crustal earthquake was reported, the displacement along east-west structures like that one suggested for one of the fault plane in our focal mechanism solution seems to be an efficient mechanism to accommodate differences in shortening from north to south in the High Andean Cordillera. Reports on damage, landslide effects as well as re-analysis of intensities associated with the new seismic source estimations for the 1958 Las Melosas earthquake are presented to further estimate the hazard to which this zone, and others along the western foothills of the Andes, is exposed.
KW - Andean Cordillera
KW - Crustal seismicity
KW - Neotectonics
KW - Seismic hazard
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U2 - 10.1016/j.pepi.2008.03.015
DO - 10.1016/j.pepi.2008.03.015
M3 - Article
AN - SCOPUS:67349274996
SN - 0031-9201
VL - 175
SP - 26
EP - 36
JO - Physics of the Earth and Planetary Interiors
JF - Physics of the Earth and Planetary Interiors
IS - 1-2
ER -