Geodetic Model of the 2018 Mw 7.2 Pinotepa, Mexico, Earthquake Inferred from InSAR and GPS Data

Abstract

ABSTRACT Investigating the interaction between slow-slip events (SSEs) and large earthquakes provides insights into earthquake-triggering mechanisms and is crucial for earthquake hazard assessment. In this study, we used Sentinel-1 Interferometric Synthetic Aperture Radar and Global Positioning System (GPS) data to estimate the source parameters of the 2018 Mw 7.2 Pinotepa, Mexico, earthquake. The results show that the earthquake ruptured both the seismogenic zone and a long-term SSE area, with two asperities ruptured during the event. GPS time-series data indicate that an SSE was initiated approximately during March 2017 below Oaxaca; the SSE ruptured an area below the source region of the Pinotepa earthquake and intruded into the seismogenic zone. The spatiotemporal proximity may suggest that the SSE triggered the Pinotepa earthquake. We propose that the triggering mechanism may either have been Coulomb stress loading or weakening of the source area by fluid migration. Furthermore, we calculated the seismic moment deficit and Coulomb failure stress changes and conclude that the Oaxaca area still has the potential for large earthquakes.