Abstract

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. Analysis of new InSAR data through August 2016 indicates that the spatial pattern of uplift is relatively unchanged but the amplitude of uplift has significantly decreased 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 continuous 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 InSAR-derived 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 displacements. Opening rates are halved (6.8 ± 1.25 × 106 m3/yr) compared to inferred values using data prior to 2010. Subsurface heterogeneity is accounted for by assigning elastic parameters based on local seismic tomography in a finite-element model. Surface displacements (or inferred volume change estimates) for heterogeneous models compared to homogeneous models are amplified by up to 7% within a 10 km radius of the center of uplift.

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