T51D-2919
Characterization of seismic clusters in the 2014 Iquique seismic sequence
Friday, 18 December 2015
Poster Hall (Moscone South)
Efrain Rivera1, Sergio Ruiz2, Felipe Leyton3, Hélène Lyon-Caen4, Andrei Maksymowicz2 and Raul I Madariaga4, (1)Universidad de Chile, Departamento de Geología, Facultad de Ciencias Físicas y Matemáticas, Santiago, Chile, (2)Universidad de Chile, Departamento de Geofísica, Facultad de Ciencias Físicas y Matemáticas, Santiago, Chile, (3)Universidad de Chile, Centro Sismológico Nacional, Facultad de Ciencias Físicas y Matemáticas, Santiago, Chile, (4)Ecole Normale Supérieure Paris, Laboratoire de geologie, CNRS, Paris, France
Abstract:
On April 1, 2014, the Iquique earthquake (Mw 8.1) occurred in Northern Chile. This earthquake was preceded and followed by a complex seismic sequence which was well recorded by the IPOC/CSN network, and also by a temporary network deployed by CSN a few days before the Mainshock. The precursory events were recorded since 2008; they were characterized by the episodic occurrence of clustered events of magnitudes between Ml 2.5 – 5.0. The clusters were repeated in time before and after the main Iquique earthquake. We identified the seismic clusters, we localized them and we relocalized events within the clusters using a double-difference algorithm. We also computed regional moment tensor solutions by waveform inversion of the broadband data. Most of these events were located in a within a band of 50 km width from the trench. These events were clustered around three sites inside this band which have been active before and after the main-shock. They could be caused by fracture zones, concentrated below the eroded continental wedge that extends for about 50 km landward from the trench. We propose that the spatial localization and temporal occurrence of these clustered events was associated with a complex rupture process of the Iquique earthquake, which was preceded by a slow slip event, and a complex pattern of fore- and aftershock seismicity.
