Andean earthquakes triggered by the 2010 Maule,Chile (Mw 8.8) earthquake: Comparisons of geodetic,seismic and geologic constraints |
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| Institution: | 1. Institute of Volcanology and Seismology FEB RAS, Piip boulevard 9, Petropavlovsk-Kamchatsky 683006, Russian Federation;2. GZG, Abteilung Geochemie, Universität Göttingen, Goldschmidtstrasse 1, 37077 Göttingen, Germany;3. Department of Earth Sciences, Dickinson College, Carlisle, PA 17013, United States of America;4. Institute of Geology of Ore Deposits, Petrography, Mineralogy and Geochemistry RAS, Staromonetnyi pereulok 35, Moscow 119017, Russian Federation |
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| Abstract: | The Maule, Chile, (Mw 8.8) earthquake on 27 February 2010 triggered deformation events over a broad area, allowing investigation of stress redistribution within the upper crust following a mega-thrust subduction event. We explore the role that the Maule earthquake may have played in triggering shallow earthquakes in northwestern Argentina and Chile. We investigate observed ground deformation associated with the Mw 6.2 (GCMT) Salta (1450 km from the Maule hypocenter, 9 h after the Maule earthquake), Mw 5.8 Catamarca (1400 km; nine days), Mw 5.1 Mendoza (350 km; between one to five days) earthquakes, as well as eight additional earthquakes without an observed geodetic signal. We use seismic and Interferometric Synthetic Aperture Radar (InSAR) observations to characterize earthquake location, magnitude and focal mechanism, and characterize how the non-stationary, spatially correlated noise present in the geodetic imagery affects the accuracy of our parameter estimates. The focal mechanisms for the far-field Salta and Catamarca earthquakes are broadly consistent with regional late Cenozoic fault kinematics. We infer that dynamic stresses due to the passage of seismic waves associated with the Maule earthquake likely brought the Salta and Catamarca regions closer to failure but that the involved faults may have already been at a relatively advanced stage of their seismic cycle. The near-field Mendoza earthquake geometry is consistent with triggering related to positive static Coulomb stress changes due to the Maule earthquake but is also aligned with the South America-Nazca shortening direction. None of the earthquakes considered in this study require that the Maule earthquake reactivated faults in a sense that is inconsistent with their long-term behavior. |
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| Keywords: | Tectonic deformation Stresses: crust and lithosphere Satellite geodesy Seismic cycle related deformations |
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