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Abstract

Uturuncu volcano in Bolivia is a 6008m high stratovolcano located above the Altiplano-Puna Magma Body (APMB), the world’s largest zone of silicic partial melt. Uturuncu forms part of the Altiplano-Puna volcanic complex (APVC) and has not had eruptions in the past 250ka. However, Uturuncu sits in the centre of a ~150 km wide deformation anomaly with at least 50 years of instrumented records of uplift from levelling, Global Navigation Satellite Systems and satellite remote sensing. Synthetic Aperture Radar interferograms indicate a mean maximum rate of uplift along the satellites' line-of-sight of 1cm/yr between 1992 and 2011, followed by a decrease in mean maximum velocities to values of ~0.3cm/yr. Three-component GPS data from a site located at ~5500 m elevation on the western slopes of Uturuncu corroborates satellite-based data. Here we present campaign-style GNSS measurements collected at 11 stations between March 2010 and November 2022 during seven joint and simultaneous microgravity and GNSS surveys along a 65 km long east-west transect from Laguna Celeste located to the east of Uturuncu to Laguna Colorada located to the west. The results enable us to constrain the three-dimensional displacement field of the deformation anomaly and tackle ambiguities from interferometric data regarding north-south displacements across the main area of uplift. Additionally, microgravimmetric data can be updated for measured vertical displacements and compared to results obtained from inferred displacements from satellite data. This will allow us to put further constraints on the driving mechanisms behind the enigmatic ground deformation in the Altiplano-Puna region of southern Bolivia.