From Ecuador to Patagonia: Andean deformation from InSAR 1992-2007

We use Interferometric Synthetic Aperture Radar (InSAR) observations from 6 satellites (ERS-1, ERS-2, ENVISAT, RADARSAT, ALOS, and JERS-1) along with published GPS displacements to constrain the myriad deformational processes in the central and southern Andes between 1992-2007. In this contribution, we review the types of deformation that are occurring (volcanoes, earthquakes, post-seismic and inter-seismic deformation, glaciers, groundwater, and anthropogenic processes) and present new observations and models of these processes. In the central Andes, InSAR observations have been possible in all seasons and have documented numerous sources of deformation: at least 7 volcanic areas, more than a dozen earthquakes (5 < Mw < 8.4), both natural and human-induced groundwater movements, and some signals that are mysterious. On the other hand, it is difficult to constrain inter-seismic deformation given the various sources of noise in the InSAR data, including: changes in the water vapor content of the troposphere, perturbations in the ionosphere, and uncertainty in the precise orbital positions of the satellites. In the southern Andes, because of the more humid climate, deformation measurements with C-band radar are only successful during the austral summer. In addition, due to a lack of data acquisitions, observations are limited to only a subset of the potentially active volcanoes and a fraction of the time period for which there is satellite data. In spite of the difficulties, we observe deformation at at least two two volcanoes, from the oil production in the San Jorge basin, as well as motion of glaciers at the Northern and Southern Patagonian Icefields. Preliminary L-band InSAR data from ALOS indicates great potential for further illuminating deformational processes in the southern Andes.