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Published November 2016 | Supplemental Material
Journal Article Open

Triggering of the 2014 M_w7.3 Papanoa earthquake by a slow slip event in Guerrero, Mexico

Abstract

Since their discovery two decades ago, slow slip events have been shown to play an important role in accommodating strain in subduction zones. However, the physical mechanisms that generate slow slip and the relationships with earthquakes are unclear. Slow slip events have been recorded in the Guerrero segment of the Cocos–North America subduction zone. Here we use inversion of position time series recorded by a continuous GPS network to reconstruct the evolution of aseismic slip on the subduction interface of the Guerrero segment. We find that a slow slip event began in February 2014, two months before the magnitude (M_w) 7.3 Papanoa earthquake on 18 April. The slow slip event initiated in a region adjacent to the earthquake hypocentre and extended into the vicinity of the seismogenic zone. This spatio-temporal proximity strongly suggests that the Papanoa earthquake was triggered by the ongoing slow slip event. We demonstrate that the triggering mechanism could be either static stress increases in the hypocentral region, as revealed by Coulomb stress modelling, or enhanced weakening of the earthquake hypocentral area by the slow slip. We also show that the plate interface in the Guerrero area is highly coupled between slow slip events, and that most of the accumulated strain is released aseismically during the slow slip episodes.

Additional Information

© 2016 Macmillan Publishers Limited. Received 22 March 2016; Accepted 26 August 2016; Published online 03 October 2016. We thank M. Bouchon for useful comments and discussions. We thank people who maintain the cGPS networks in Guerrero (IG-UNAM) and Oaxaca (TLALOCNet programme) states, in particular J. A. Santiago at the Servicio Mareografico Nacional-UNAM, S. I. Franco at the Servicio Sismologico Nacional-UNAM and L. Salazar-Tlaczani at UNAM-IGEF. Data from INEGI were also used for the Analysis. This work has been supported by a grant from Labex OSUG@2020 (Investissements d'avenir ANR10 LABX56), and by the French spatial agency CNES (project TOSCA SSEMEX). Portions of the GPS network were supported by the National Science Foundation under award EAR-1338091, by UNAM-PAPIIT projects IN104213-2, IN109315-3 and IN110514, and by Conacyt project 178058. Author Contributions: M.R. carried out data analysis, modelling and wrote the paper. H.P. edited the paper and performed modelling. N.C. carried out GPS data processing and edited the paper. A.G. performed modelling and edited the paper. B.V. carried out modelling and edited the paper. V.K. provided GPS data and edited the paper. T.L. performed modelling. A.W. edited the paper. E.C.C. managed the GPS networks. M.C. edited the paper. The authors declare no competing financial interests.

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August 20, 2023
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