Caracterización a largo plazo de la evolución espacio-temporal de enjambres sísmicos en la zona de la Isla de la Plata, Manabí – Ecuador.

Abstract

La Plata Island Zone (ZIP), central margin of Ecuador, is a high interseismic coupling index area, with strong deformation which is released mainly aseismically (SSEs). SSEs are associated to the occurrence of seismic swarms; such as those reported in 2005, 2010, 2013. This study focuses in long-term seismic analysis to define sources similarity (OTAV, ISPT stations), improve locations and source mechanisms. This research defined that the ZIP was affected at least by 7 seismic swarms during 14 years (2002-2015), resulting in a ~2 years recurrence for swarm episodes. In addition, it was determined that after the Pedernales earthquake in April/2016, a large number of earthquakes due to a readjustment of the stress around the rupture area of the 2016 event. Cross correlation technics show that the seismicity from ZIP, is clustered in families of similar events, suggesting they share similar sources and rupture processes. The relocation and focal mechanisms show that sources are mainly located southward of the highly coupled zone and belong to the interface. As a contribution for the monitoring of SSEs in ZIP, the use of cross correlation and the defined templates, allows an early detection of SSEs. Despite the advance of knowledge about the behavior of the ZIP, it has not yet been determined their frictional characteristics, in order to know why a highly coupled zone is, how it dissipates most of the cumulative aseismic deformation. This uncertainty leads to do not dismiss the generation of earthquakes with destructive effects in the central margin of Ecuador.