Largest aftershock nucleation driven by afterslip during the 2014 Iquique sequence

This is a Preprint and has not been peer reviewed. The published version of this Preprint is available: https://doi.org/10.1029/2023GL104852. This is version 5 of this Preprint.

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Authors

Yuji Itoh , Anne Socquet, Mathilde Radiguet

Abstract

Various earthquake models predict that aseismic slip modulates the seismic rupture process but actual observations of such seismic-aseismic interaction are scarce. We analyze seismic and aseismic processes during the 2014 Iquique earthquake sequence. High-rate Global Positioning System (GPS) displacements demonstrate that most of the early afterslip is located downdip of the M 8.1 mainshock and is accompanied by decaying aftershock activity. An intriguing secondary afterslip peak is located ~120 km south of the mainshock epicenter. The area of this secondary afterslip peak likely acted as a barrier to the propagating mainshock rupture and delayed the M 7.6 largest aftershock, which occurred 27 hours later. Interevent seismicity in this secondary afterslip area ended with a M 6.1 near the largest aftershock epicenter, kicking the largest aftershock rupture in the same area. Hence, the interevent afterslip likely promoted the largest aftershock nucleation by destabilizing its source area, favoring a rate-dependent cascade-up model.

DOI

https://doi.org/10.31223/X5G08S

Subjects

Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics, Tectonics and Structure

Keywords

afterslip, High-rate GPS, Chile, The 2014 Iquique earthquake, nucleation, Postseismic deformation, GNSS, Subduction zone, megathrust earthquake

Dates

Published: 2023-03-10 16:02

Last Updated: 2023-12-21 14:21

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License

CC BY Attribution 4.0 International

Additional Metadata

Conflict of interest statement:
None