Revised interpretation of recent InSAR signals observed at Llaima volcano (Chile)

Dominique Rémy (1) , Y Chen (1) , Jean-Luc Froger (2) , Sylvain Bonvalot (1) , L. Cordoba (3) , J. Fustos

1 GET - Géosciences Environnement Toulouse
2 LMV - Laboratoire Magmas et Volcans
3 OVDAS - Observatorio Volcanológico de Los Andes del Sur

We analyzed C band and L band interferometric synthetic aperture radar (InSAR) data acquired from 2003 to 2011 to search for volcanic deformations at Llaima volcano, Southern Andes (38.69°S, 71.73°W). There, specific environmental conditions (steep slopes, snow- or ice-capped summit, dense vegetation cover, and strong tropospheric artifacts) and limited amount of radar data available make it challenging to accurately measure ground surface displacement with InSAR. To overcome these difficulties, we first performed a careful analysis of the water vapor variations using Medium-Resolution Imaging Spectrometer and Moderate Resolution Imaging Spectroradiometer near-infrared water vapor products and then we inverted wrapped interferograms for both topographic correlated phase delays and a simple model source strength. In the light of our results, we conclude that there is no detectable ground displacement related to a deep magmatic source for the 2003–2011 period and that most of the fringes observed in the interferograms were produced by tropospheric delays.

Mots clés: InSAR; atmospheric artifacts; volcano ground deformation

Domaines: Volcanologie

Dominique Rémy, Y Chen, Jean-Luc Froger, Sylvain Bonvalot, L. Cordoba, et al.. Revised interpretation of recent InSAR signals observed at Llaima volcano (Chile). Geophysical Research Letters, 2015, 42 (10), pp.3870-3879. ⟨10.1002/2015GL063872⟩. ⟨hal-01172186⟩