Statistical evidence of a seismic quiescence before the Mw8.1 Iquique earthquake, Chile

The 2014 Iquique seismic crisis (Chile), culminating with a Mw 8.1 earthquake, April 1st, highlights a complex unlocking of the North Chile subduction interface which has been considered as a seismic gap since 1877. During the year preceding this event, at least three seismic clusters were observed: in July 2013 and January and March 2014. These clusters possibly indicate aseismic slip transients accompanying the progressive destabilization of the plate contact. Recent studies have proposed large-scale slab deformation as a potential trigger for the megathrust earthquake; However, no evidence of gradual unlocking of the interface or transient deformation has yet been found in the seismic rate. To address this question, we develop a dense earthquake catalog during the fifteen months preceding the mainshock from the continuous waveform dataset recorded by the Integrated Plate Boundary Observatory Chile (IPOC) and Iquique Local Network (ILN) networks. After declustering the seismicity, a space-time analysis ...