Deformation pattern on Cerro Blanco volcanic complex (cbvc)

LÓPEZ, J. F.; BARBERO, I.; VIRAMONTE, J. G.; VÉLEZ, M. L.; EUILLADES, L.; BLANCO, M.

Puerto Varas

Congreso; Cities on Volcanoes 9 - Understanding volcanoes and society: the key for risk mitigation; 2016

IAVCEI - SERNAGEOMIN

CerroBlanco Volcanic Complex (CBVC) located in Catamarca province in Argentina, isthe youngest caldera of the southern segment of the Central Andes with the lasteruption 4.2 ka ago. In this work we present the deformation pattern rates ofthe CBVC by two commonly applied techniques to monitoring volcano: DifferentialInterferometry Synthetic Aperture RADAR (DInSAR) and GNSS. Firstly, Envisatframes from 2003 to 2010 and COSMO-SkyMed frames from 2012 to 2015 wereprocessed by using SBAS-DInSAR methodology obtaining a subsidence rate of ~ 1cm/yr and ~ 0.7 cm/yr, respectively. Based on DInSAR results, analytical modelsof the deformation source were generated. The CBCV GNSS-GPS geodynamic networkis defined for five benchmarks around the volcano. The observation surveys werecarried out yearly in 2004, 2013 and 2015 that were processed giving similarsubsidence rates than DINSAR. Also, we have compared our results with otherauthors that denote a continuous subsidence (ranging from -2.5 cm/yr to -0.7cm/yr). According to modeling results, subsidence could be best fitted with anellipsoidal oblate cavity, which is a horizontal lens whose extension underliesmuch of the CBVC or by a sill type source. This magmatic body is presumablylocated on the center to CBCr at about 6 km of depth. We interpret thisdeformation as a rearrangement of the volcanic system after the 4.2 ka eruptionwhen volume of volcanic material from 56 to 75 km3 was emitted. A continuousdecrease in deflation rate has been observed but further studies had to be doneto determine whether deformation goes to a change in sign and a possiblereactivation or not. This enhances the importance of continuous monitoringdeformation as useful indicator of activity at CBVC.