Microseismicity appears to outline highly coupled regions on the Central Chile megathrust

This is a Preprint and has not been peer reviewed. The published version of this Preprint is available: https://doi.org/10.1029/2021JB022252. This is version 2 of this Preprint.

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Authors

Christian Sippl , Marcos Moreno , Roberto Benavente 

Abstract

We compiled a novel microseismicity catalog for the Central Chile megathrust (29-35◦S), comprising 8750 earthquakes between 04/2014 and 12/2018. These events describe a pattern of three trenchward open half-ellipses, consisting of a continuous, coast-parallel seismicity band at 30-45 km depth, and narrow elongated seismicity clusters that protrude to the shallow megathrust and separate largely aseismic regions along strike. To test whether these shapes could outline highly coupled regions (“asperities”) on the megathrust, we invert GPS displacement data for interplate locking. The best-fit locking model does not show good correspondence to seismicity, possibly due to lacking resolution. When we prescribe high locking inside the half-ellipses, however, we obtain models with similar data fits that are preferred according to the Bayesian Information Criterion (BIC). We thus propose that seismicity on the Central Chile megathrust may outline three adjacent highly coupled regions, two of them located between the rupture areas of the 2010 Maule and the 2015 Illapel earthquakes, a segment of the Chilean margin that may be in a late interseismic stage of the seismic cycle.

DOI

https://doi.org/10.31223/X56S3B

Subjects

Physical Sciences and Mathematics

Keywords

Megathrust, Mogi Doughnut, Seismicity, Segmentation

Dates

Published: 2020-11-12 17:24

Last Updated: 2021-11-05 10:27

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License

CC BY Attribution 4.0 International

Additional Metadata

Conflict of interest statement:
None

Data Availability (Reason not available):
Not available yet (will come with article acceptance)

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