Unrest of Chiles – Cerro Negro volcanic complex: A binational Ecuador – Colombia effort

Thursday, 18 December 2014
Mario Calixto Ruiz1, Diego Gomez2, Roberto Torres2, Oscar Cadena2, Patricia A Mothes1, Juan Camilo Anzieta1, Daniel Alejandro Pacheco1, Benjamin Bernard3, Wilson Acero1, Silvana Hidalgo1, Wilson Enriquez1 and Andrea Cordova1, (1)Instituto Geofisico EPN - Ecuador, Quito, Ecuador, (2)Servicio Geológico Colombiano Pasto, Pasto, Colombia, (3)Instituto Geofísico de la Escuela Politécnica Nacional, Quito, Ecuador
The increasing seismic activity at the area of Chiles – Cerro Negro volcanic complex, located at the Ecuador-Colombian border, has been jointly monitored by the Instituto Geofisico – Ecuador and the Observatorio Vulcanologico y Sismologico de Pasto OVSP, a division of the Servicio Geologico Colombiano. Since April 2013, three seismic swarms have been detected in this area and more than 100.000 events are recorded since November 2013. The largest and more recent swarm has a daily average of 676 events between March and June 2014. Currently a seismic network of 8 seismic stations (5 in the Colombian and 3 in Ecuadorean side) are deployed in this area. Epicenters of more than 315 seismic events with magnitudes Ml>2.0 and 10 or more phases are located in an area 1-4 km south of Chiles volcano with shallow depths (up to 14 km). Most of events have magnitudes between 1.0 to 4.0. Nine events have magnitudes larger than 4.0 and the largest event occurred on April 30. 2014 with a local magnitude of 4.7 and inverse-transcurrent component focal mechanism. Waveforms and spectral patterns define these events as volcano-tectonic. Events with large magnitudes (above 3.0) show a very long-period component. Hot spring and deformation measurements also show signals of volcanic unrest.