Deflation detected at Descabezado Grande Volcano, Chile, between 2007 and 2011

GEMMA ACOSTA; EUILLADES, PABLO A.; GUSTAVO SOSA; EUILLADES, LEONARDO

Helsinki

Workshop; Fringe 2017 Workshop; 2017

European Space Agency

Volcán Descabezado Grande is part of the Descabezado Grande-Quizapú Volcanic Complex, located in the Maule region - Chile at 35°35´11?S, 70°44´38? W. It is a late Pleistocene to Holocene andesitic-to-rhyodacitic stratovolcano with an ice-filled summit crater of 1.5 km diameter. The volcano reaches a height of 3830m with a basal diameter of 11km (Benavente Zolezzi, 2010).Descabezado Grande has been active for the last 300k years, being its volcanic products andesitic to rhyodacitic lavas, tefras and ash-flows reaching up to 7km in length. Last eruption occurred in June 1932, shortly after the great eruption of the neighboring volcano Quizapú. During this eruption, a crater of ~900m diameter, known as ?Respiradero?, opened in the northern flank, generating an ash plume several kilometers high and 8km length pyroclastic fall deposits. Recent activity is weak, consisting in a few fumaroles detected at Respiradero crater during 2009, as reported by OVDAS-SERNAGEOMIN (http://www.sernageomin.cl). In this contribution, we present the first results obtained by DInSAR time-series processing of the described area. We analyzed 17 L-Band ALOS/PALSAR stripmap scenes, acquired between January 2007 and December 2010. We computed 39 differential interferograms, and combined them by using the well-known Small Baseline Subsets (SBAS) technique (Berardino et al., 2002). Topographic phase removal was performed with the SRTM arc1 Digital Elevation Model (Jarvis et al., 2006).Our results suggest that, between 2007 and 2011, the Descabezado Grande presented a deflation process of ~3cm/yr. The observed pattern is oval shaped and extends to the north of the volcano edifice. Maximum deformation is located between the summit and the Respiradero craters.ReferencesBenavente Zolezzi, O.M., 2010. Actividad Hidrotermal Asociada a los Complejos Volcánicos Planchón-Peteroa y Descabezado Grande-Quizapu-Cerro Azul, 35° sy 36os, Zona Volcánica Sur, Chile. Universidad de Chile, Santiago de Chile.Berardino, P., Fornaro, G., Lanari, R., Sansosti, E., 2002. A New Algorithm for Surface Deformation Monitoring Based on Small Baseline Differential SAR Interferograms. IEEE Trans. Geosci. Remote Sens. 40, 2375?2383.Jarvis, A., Reuter, H.I., Nelson, A., Guevara, E., 2006. Hole-filled SRTM for the globe Version 3. CGIAR-CSI SRTM 90m Database: http://srtm.csi.cgiar.org.