GPS constraints on the 2011-2012 Oaxaca slow slip event that preceded the 2012 March 20 Ometepec earthquake, southern Mexico
Por:
Graham, SE, DeMets, C, Cabral-Cano, E, Kostoglodov, V, Walpersdorf, A, Cotte, N, Brudzinski, M, McCaffrey, R, Salazar-Tlaczani, L
Publicada:
1 jun 2014
Resumen:
We model measurements from 19 continuous GPS stations to determine the location and magnitude of a slow slip event (SSE) below southern Mexico that began in late 2011 and remained active up to the 2012 March 20 Mw = 7.4 Ometepec earthquake. Modelling of the space-time evolution of the SSE indicates that it initiated in 2011 November, migrated westward ~2.6 kmper day along the subduction interface, and reached the eventual earthquake source regioñ1 month before the 2012 March 20 earthquake occurred, in the waning stage of the SSE. The maximum slip for the SSE, ~100 mm, occurred ~100 km east of the earthquake rupture zone, in contrast to slip of 10-20mm proximal to the Ometepec rupture zone. The SSE was focused downdip from the seismogenic zone everywhere along its ~300-km-wide slip region and had a cumulative moment release of 3.0 times 1019 N•m (Mw = 6.9), similar to SSEs in 2004 and 2006 along this same area of the subduction interface. We calculate Coulomb stress changes as a result of slip during the SSE and find small but positive stress changes for the source region of the Ometepec earthquake. Our results are consistent with the hypothesis that the SSE triggered the Ometepec earthquake, although they are insufficient to demonstrate causality. © The Authors 2014. Published by Oxford University Press on behalf of The Royal Astronomical Society.
Filiaciones:
Cabral-Cano, E:
Univ Nacl Autonoma Mexico, Inst Geofis, Mexico City 04510, DF, Mexico
Kostoglodov, V:
Univ Nacl Autonoma Mexico, Inst Geofis, Mexico City 04510, DF, Mexico
Salazar-Tlaczani, L:
Univ Nacl Autonoma Mexico, Inst Geofis, Mexico City 04510, DF, Mexico
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