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An 8month slow slip event triggers progressive nucleation of the 2014 Chile megathrust
- The mechanisms leading to large earthquakes are poorly understood and documented. Here we characterize the long-term precursory phase of the 1 April 2014 M(w)8.1 North Chile megathrust. We show that a group of coastal GPS stations accelerated westward 8months before the main shock, corresponding to a M(w)6.5 slow slip event on the subduction interface, 80% of which was aseismic. Concurrent interface foreshocks underwent a diminution of their radiation at high frequency, as shown by the temporal evolution of Fourier spectra and residuals with respect to ground motions predicted by recent subduction models. Such ground motions change suggests that in response to the slow sliding of the subduction interface, seismic ruptures are progressively becoming smoother and/or slower. The gradual propagation of seismic ruptures beyond seismic asperities into surrounding metastable areas could explain these observations and might be the precursory mechanism eventually leading to the main shock.
Author details: | Anne SocquetORCiD, Jesus Pina Valdes, Jorge JaraORCiD, Fabrice CottonORCiDGND, Andrea Walpersdorf, Nathalie Cotte, Sebastian von SpechtORCiDGND, Francisco Ortega-Culaciati, Daniel Carrizo, Edmundo Norabuena |
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DOI: | https://doi.org/10.1002/2017GL073023 |
ISSN: | 0094-8276 |
ISSN: | 1944-8007 |
Title of parent work (English): | Geophysical research letters |
Publisher: | American Geophysical Union |
Place of publishing: | Washington |
Publication type: | Article |
Language: | English |
Year of first publication: | 2017 |
Publication year: | 2017 |
Release date: | 2020/04/20 |
Tag: | GPS; precursor; seismology; subduction |
Volume: | 44 |
Number of pages: | 8 |
First page: | 4046 |
Last Page: | 4053 |
Funding institution: | LabeX OSUG; SMINGUE; IRD AO-Sud; INSU-Aleas grants; CONICYT through "Becas Chile" PhD fellowships; Proyecto Fondecyt [11140904]; [PNTS-2014-08] |
Organizational units: | Mathematisch-Naturwissenschaftliche Fakultät / Institut für Geowissenschaften |
Peer review: | Referiert |