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Seafloor Geodesy Unveils Seismogenesis of Large Subduction Earthquakes in México
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Abstract
Seafloor geodesy may lead to deep understanding of subduction systems and seismogenesis. Based on measurements of near-trench deformations of the oceanic and overriding plates, in this investigation we elucidate the tectonic and mechanical processes leading to the Mw7.0 Acapulco, Mexico, earthquake in 2021 at the heart of the Guerrero seismic gap. We exploit unprecedented ocean-bottom observations using new ultra-long-period ‘tilt mechanical amplifiers’, along with hydrostatic pressure, GNSS, and satellite InSAR data. The joint inversion of all these geodetic data, template matching seismicity and repeating earthquakes, revealed the first two shallow slow slip events (SSEs) observed in Mexico. The first one migrated from the trench to the earthquake hypocenter before rupture, and the second one occurred following an Mw7.7 long-term deeper SSE induced by the earthquake. Near-trench oceanic-crust episodic deformations (i.e., tilt transients) associated with shallow and deep synchronous decoupling of the plate interface reveal the occurrence of ‘slab-pull surges’ across the subduction channel prior to three M7+ regional earthquakes including the Acapulco event.
DOI
https://doi.org/10.31223/X5372H
Subjects
Earth Sciences, Physical Sciences and Mathematics
Keywords
seafloor geodesy, Seafloor tiltmeters, Mexico, slow slip events, Seafloor pressure gauges, Slab pull surges, GNSS inversion, Template matching seismicity, Repeating earthquakes, Acapulco earthquake, slow earthquakes
Dates
Published: 2025-03-26 05:38
Last Updated: 2025-03-26 20:18
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License
CC-By Attribution-NonCommercial-NoDerivatives 4.0 International
Additional Metadata
Data Availability (Reason not available):
Codes used for the analysis are available upon request. Seafloor pressure and tilt data are restricted until the end of 2028 due to confidentiality clauses of the SATREPS-UNAM project. GNSS data are restricted according to the data distribution policy of the National Seismological Service (SSN) and the Department of Seismology of the Institute of Geophysics, UNAM. Exceptions may be granted after discussion with project leaders as long as the motivation is to establish substantive scientific collaboration. Broadband seismological data are unrestricted and can be obtained on request from the SSN.
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