TY  - JOUR
A1  - Socquet, Anne
A1  - Valdes, Jesus Pina
A1  - Jara, Jorge
A1  - Cotton, Fabrice Pierre
A1  - Walpersdorf, Andrea
A1  - Cotte, Nathalie
A1  - von Specht, Sebastian
A1  - Ortega-Culaciati, Francisco
A1  - Carrizo, Daniel
A1  - Norabuena, Edmundo
T1  - An 8month slow slip event triggers progressive nucleation of the 2014 Chile megathrust
JF  - Geophysical research letters
N2  - 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.
KW  - seismology
KW  - GPS
KW  - subduction
KW  - precursor
Y1  - 2017
U6  - https://doi.org/10.1002/2017GL073023
SN  - 0094-8276
SN  - 1944-8007
VL  - 44
SP  - 4046
EP  - 4053
PB  - American Geophysical Union
CY  - Washington
ER  -