Source study and tectonic implications of the historic 1958 Las Melosas crustal earthquake, Chile, compared to earthquake damage

Patricia Alvarado, Sergio Barrientos, Mauro Saez, Maximiliano Astroza, Susan Beck

Research output: Contribution to journalArticle

21 Scopus citations

Abstract

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.

Original languageEnglish (US)
Pages (from-to)26-36
Number of pages11
JournalPhysics of the Earth and Planetary Interiors
Volume175
Issue number1-2
DOIs
StatePublished - Jun 1 2009

Keywords

  • Andean Cordillera
  • Crustal seismicity
  • Neotectonics
  • Seismic hazard

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Geophysics
  • Physics and Astronomy (miscellaneous)
  • Space and Planetary Science

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