Estudio del coulomb stress en la influencia potencial de la actividad volcánica holocénica y sísmica en el nido de Pisayambo, Tungurahua.

Abstract

The Pisayambo Seismic Nest (NSP) located in the Eastern Cordillera of Ecuador, east of Pillaro Tungurahua, has a high rate of low-magnitude seismicity at 5-30 km depths. Deposits and volcanic centers of Late Pleistocene age belonging to the Ecuadorian Rhyolitic Province (ERP) have also been found in the area. In this study, we investigate what effect Coulomb Stress changes and strain generated by seismicity from the NSP can have on potentially provocating or inhibiting eruptive activity at nearby volcanic centers. We focus on a significant (Mw 5.0) surface faulting event that occurred near Pisayambo Lake on March 26, 2010, while South Pisayambo Vent was the rhyolitic center focused for this study. A high-resolution slip model (finite fault model) based on seismic and InSAR data was input into the Coulomb 3.3 software. With this model, we characterize the effect that seismicity at Pisayambo may have on both the ERP volcanic centers and the surrounding NSP faults. The results show that the March 26, 2010 event generated compressional strain (volumetric compression) in the shallow region of South Pisayambo Vent, which tends to close possible fissures and volcanic conduits. Similarly, Coulomb Stress Change demonstrated that the March 26, 2010 event mainly generated stress release zones in the surrounding faults.