Suitability Of ALOS2/PALSAR ScanSAR Data For Computing Deformation Time Series: The Copahue Volcano Study Case.

GUSTAVO SOSA; EUILLADES, PABLO A.; VELEZ, MARÍA LAURA; EUILLADES, LEONARDO; BLANCO, MAURO

Helsinki

Workshop; Fringe 2017 Workshop; 2017

European Space Agency

Copahue-Caviahue volcanic complex is located in the province of Neuquen, Argentina, at 37.5°S, 71.1°W. It is constituted by the Caviahue caldera and the Copahue volcano edifice at the border between Argentina and Chile. Copahue volcano is one of the most active volcanoes in Argentina. Historical eruptions have been reported on 1992, 1995 and 2000. Two villages are situated at 5 and 9 km from the crater, increasing risk level. The active crater host an acidic hot lake with ph<1 and temperatures up to 60°.Previous works addressing crustal deformation in this area were performed by using ENVISAT, ERS and COSMO-Skymed images acquired between 2002 and 2013 [1]. They show a deflation process centered at the edifice?s northern flank, which acted between 2004 and 2010 at a rate of 2 cm/year. Inverse modeling of these results placed the deformation source at 4 km depth below the volcano, suggesting a relationship with the oscillations of the brittle-ductile boundary where leakage of brines and steams would produce depressurization of the system.After Chilean 8.8 Mw earthquake on February 27 2010, several changes where observed, mainly related with an increment in local seismicity inside Caviahue caldera. Furthermore, two eruptions produced during 2013 and 2014 [2]. SBAS-DinSAR time series show that, since 2011, the volcano inflates at a rate of around 7 cm/year until at least middle 2014. Inflation pattern is located exactly in the same region where deflation was previously detected [3] [4].In this work we analyze the suitability of ALOS2/PALSAR data for characterizing deformation related with the Copahue volcano area. Acquisition frequency in WBD (ScanSAR mode) is about one scene per month, which makes it potentially useful for volcano deformation characterization via time series processing.We processed a dataset composed of scenes acquired in WBD (ScanSAR) mode between November 2014 and November 2016. We were not able to compute coherent interferograms between scenes acquired during 2014 and scenes acquired after February 2015. However, interferograms between scenes acquired after May 2015 show very good degree of interferometric correlation.Results show that, after the uplift phase between 2012 and 2015, the system seems to stabilize and no clear deformation signal associated with the volcano is detectable. [1] María Laura Velez, Pablo Euillades, Alberto Caselli, Mauro Blanco, Jose Martínez Díaz. Deformation of Copahue volcano: Inversion of InSAR data using a genetic algorithm. Journal of Volcanology and Geothermal Research 202 (2011) 117?126.[2] Simthsonian Institution ? Global Volcanism Program. http://volcano.si.edu/volcano.cfm?vn=357090. Accesed on October 16 2015.[3] M.L. Velez, P. Euillades, M. Blanco and L. Euillades. Ground Deformation Between 2002 and 2013 from InSAR Observations. Copahue Volcano, Active Volcanoes of the World, DOI 10.1007/978-3-662-48005-2_8. Springer-Verlag Berlin Heidelberg 2016.[4] Rayner De Ruyt, Pablo Euillades, Leonardo Euillades. Identificación del Campo de Deformación Cortical del Complejo Volcánico Copahue (CVCC), mediante el Algoritmo DinSAR-SBAS. XXIII Jornadas de Jóvenes Investigadores Grupo Montevideo. 2015.