Caracterización de los procesos sísmicos y asísmicos de la zona de Punta Galera, a través del estudio de enjambres sísmicos, y su influencia sobre la génesis de los grandes terremotos del margen norte de Ecuador

Abstract

The Punta Galera-Mompiche zone (PGMZ) is a low inter-seismic coupling area located along the northern Ecuadorian margin (latitudes 0.3ºN and 1.2ºN and longitudes between 80.4ºW and 79.7ºW). The PGMZ separates two zones of strong coupling, with significant earthquakes occurring in 1942 and 2016 to the South and in 1958 to the North.). An analysis of continuous data from the IU-IRIS station OTAV recorded over the course of 15 years determined a recurrence interval of 2 years for seismic swarms and SSEs. In this study, we extend the approach of Vaca et. al. (2018) and cross-correlate template waveforms from the PGMZ as recorded at OTAV for the period 2016-2018. A set of multiple families of similar events is obtained, and, via an analysis of the temporal distribution of these events, determine that a new seismic swarm occurred in June 2017. Additionally, this new swarm appears to be associated with a slip acceleration with SSE behavior on GPS time series during post-seismic period. . Relocation of events from families tends to form clusters, and further observations of focal mechanism solutions, highlight sources located in the interface. The different behavior observed between zones with high interseismic coupling and the PGMZ, which almost continuously release seismic moment, seems to be related to the frictional properties that are acting both during the interseismic and the post-seismic period.