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- Title
Statistical Analysis of the Preparatory Phase of the M<sub>w</sub> 8.1 Iquique Earthquake, Chile.
- Authors
Aden‐Antóniow, F.; Satriano, C.; Bernard, P.; Poiata, N.; Aissaoui, E.‐M.; Vilotte, J.‐P.; Frank, W. B.
- Abstract
The 2014 Iquique seismic crisis in Chile, culminating with a Mw 8.1 earthquake on 1 April, highlights a complex unlocking of the Northern Chilean subduction that has been considered a seismic gap since 1877. During the year preceding this event, at least three clusters of seismic activity have been reported: in July 2013 and January and March 2014. Recent studies have proposed large‐scale slab deformation as a potential trigger for the megathrust earthquake, and these clusters possibly indicate aseismic slip transients accompanying the progressive destabilization of the plate contact. However, no evidence of gradual unlocking of the interface or transient deformation has yet been found in the seismicity rate. To address this question, we develop a dense earthquake catalog covering 15 months preceding the mainshock and derived from the continuous waveform data set recorded by the Integrated Plate Boundary Observatory Chile (IPOC) and Iquique Local Network (ILN) networks. After declustering the seismicity, a space‐time analysis highlights a large‐scale acceleration of the seismicity along the interface accompanied by a deceleration of intermediate‐depth earthquakes. We demonstrate the existence of a seismic quiescence downdip of the mainshock rupture before the July 2013 cluster. We propose that this seismic quiescence potentially highlights fluid circulation and/or aseismic motion along upper‐plate crustal fault(s). Key Points: Evidences of a year‐long preparatory phase of the Iquique earthquakes are found in a new seismic catalogA Kolmogorov‐Smirnov one‐sample test applied to the background seismicity suggests a large‐scale acceleration of the seismicity rateA local Kolmogorov‐Smirnov one‐sample test reveals a seismic quiescence close to the Iquique earthquake coseismic rupture area
- Subjects
IQUIQUE (Chile); CHILE; EARTHQUAKES; SEISMIC response; SURFACE fault ruptures; SUBDUCTION zones
- Publication
Journal of Geophysical Research. Solid Earth, 2020, Vol 125, Issue 6, p1
- ISSN
2169-9313
- Publication type
Article
- DOI
10.1029/2019JB019337