Villarrica, Llaima, and Calbuco volcanoes are the most active and dangerous volcanoes in the Southern Andes, and we use Interferometric Synthetic Aperture Radar (InSAR) observations from multiple satellites (ERS-2, ENVISAT, ALOS, RADARSAT-2, COSMO-SkyMed, TerraSAR-X, Sentinel-1A and ALOS-2) to constrain ground deformation that spans episodes of unrest and eruption at all three volcanoes between 2002 and 2015. We find episodes of ground deformation at each volcano, which we invert using analytic elastic half space models to make some of the first geophysical inferences about the source depths of potential magma chambers. At Llaima, we interpret that the VEI 2 April 3 2009 eruption was preceded by ~6-15 cm of precursory ground uplift one month before from a source ~5 km below the surface on the western side of the edifice. The VEI 2 March 3 2015 Villarrica eruption was followed by a short lived uplift of 5 cm in the SE part of the volcano from a source depth of ~6 km.

New continuous GPS observations near the summit of Uturuncu volcano, Bolivia, indicate an average uplift rate of 2.4 ± 1.9 mm/yr between April 2010 and November 2015, while previous interferometric synthetic aperture radar (InSAR) observations between May 1992 and January 2011 predict an average vertical uplift rate of 7 ± 2 mm/yr. However, the GPS time series is better fit with a timedependent function, such that the uplift rate in 2010 is less than 2 mm/yr and in 2015 may be as high as 9 mm/yr. Motivated by indications of a non-constant rate in the continuous GPS time series, we examine to what extent past InSAR measurements may have been temporally aliased. We present evidence that decreased uplift since 2004 is permitted by available InSAR and is consistent with a lower average GPS rate since 2010. We discuss how these variable rates may affect previously proposed magmatic models at Uturuncu including diapir ascent and reservoir pressurization. In particular, we explore a "dipole" reservoir model consisting of a magma source in the lower crust and sink in the middle crust for which variation in magma supply could explain sub-decadal fluctuations in deformation rate. Inversion of multiple InSAR data sets using homogeneous models constrains the deeper reservoir to 55-80 km depth (lower crust and upper mantle) and the shallower reservoir to 20-35 km. Consistent with previous work, the inferred ratio of volume change between the source:sink (i.e., deep:shallow) reservoirs is up to 10:1. We also incorporate new seismic tomography results in a 3D finite-element model to explore the combined effects of multiple sources and material heterogeneity on surface deformation. An important conclusion from our modeling efforts is that the commonly used diagnostic ratio of maximum radial to vertical surface displacements for shape of the deformation source is affected by both the presence of multiple reservoirs and subsurface heterogeneity. Ultimately, the dipole and diapir models have unresolved shortcomings given the entire suite of available geophysical data, but both provide valuable insight into the conditions for magmatic ascent in the Central Andes.

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Interferometric synthetic aperture radar (InSAR) and GPS measurements beyond 2010 are presented for the first time for the Lazufre volcanic center in the Central Andes. Vertical uplift at Lazufre was known to affect an area >50 km in diameter at rates exceeding 3 cm/yr between 1997 and 2010. Analy sis of new InSAR data through August 2016 indicates that the spatial pattern of uplift is relatively unchanged but the amplitude of uplift has significantly de creased to <1.5 cm/yr since at least December 2011. We present a time series inversion for InSAR data between 1996 and 2016 that is well fit by a double exponential model, with an inflection point occurring in 2006. For two con tinuous GPS stations installed within the deformation footprint in November 2010, we have determined vertical velocities through 2014 or 2015 (depending on the station) that agree with contemporaneous InSARderived velocities. Velocities from campaign GPS benchmarks established in November 2011 and reoccupied in March 2014 are also presented. We use a previously proposed model of an inflating sill at 10 km depth to explain geodetically observed dis placements. Opening rates are halved (6.8 ± 1.25 × 10 6 m 3 /yr) compared to in ferred values using data prior to 2010. Subsurface heterogeneity is accounted for by assigning elastic parameters based on local seismic tomography in a finiteelement model. Surface displacements (or inferred volume change esti mates) for heterogeneous models compared to homogeneous models are ampli fied by up to 7% within a 10 km radius of the center of uplift.