Construcción de un nuevo modelo heterogéneo de velocidades sísmicas de ondas P en la subducción ecuatoriana

Abstract

The hypothesis underlying this paper is that a precise calculation of travel times should improve the hypocentral determination of an earthquake. To this end, we have constructed a new seismic P-wave velocity model (NMV-3D) that adequately represents various structural heterogeneities in the lithospheres along the subduction zone of Ecuador. The construction of this model is based on the construction of a structural model of the layers that make up the two dominant tectonic plates. The main contributions of this work are to improve: (1) the thickness of the sediment layer, (2) the geometry and depth of the seismic slab (between 25 and 160 km depth), and (3) the topography of the interplate contact zone (depths between 0 to 25 km). A comparison of the geometry of the shallow and deep structures seems to point the existence of a ~ 50 km wide zone oriented ENE-WSW that separates the northern part of Ecuador from the south. The good correlation between seismicity (pre- and post-earthquake 04/2016) and the topography of the top of the Nazca plate suggests that the distribution of earthquakes migh be controlled, in part, by the structure of the subducting plate.