The use of seismic arrays to track seismo-volcanic activity, examples from Colima and Copahue volcanoes.

IBÁÑEZ, J.M., OROZCO-ROJAS, J., CISNEROS, M., BRETÓN, M., CASELLI, A., BENGOA, C., PALO, M., ALMENDROS, J., GARCÍA-YEGUAS, A., CARRIÓN, F. & ALGUACIL, G.

VOLcanoes: Understanding subsurface mass movement.

jaycee

Lugar: Dublin; Año: 2009; p. 227 - 236

Copahue Volcano, Southern Andes, Argentina, using a small-aperture, dense seismic antenna (Ibanez et al., 2008). We locate volcano-tectonic (VT) earthquakes using a procedure based on the estimate of slowness vector components and S-wave, P-wave times. VT events are located mainly along the border of the Caviahue caldera lake, South-East of Copahue volcano, at a depth of 1-3 km below the surface. The background noise shows the presence of many transients with a high correlation among the array stations in the frequency band centered at 2.5 Hz. These transients are superimposed onto an uncorrelated background seismic signal. Array solutions for these transients show a predominant slowness vector pointing to the exploited geothermal field of “Las Maquinitas” and Copahue Village, located about 6 km north of the array site. We interpret this coherent signal as a tremor generated by the activity of the geothermal field. Additionally, we have investigated the wavefield properties of the seismic signals generated by the explosions of Volcán de Colima (México). We have analysed the wavefield to understand the initial mechanism that triggered the explosive events. Our study is focused on the direct waves coming from the crater area. We have been able to identify the dominant wave types that comprise the seismic wavefield and infer, in time and space, a possible primary source mechanism for volcanic explosions.