Subsurface density structure associated with an active intrusion in the central Andes - Bolivia

Abstract

Dual frequency GPS and gravity measurements were performed during two survey campaigns in southern Bolivia in 2010 using GNSS equipment provided by the NERC GEF facility in Edinburgh. The survey area is located around Uturuncu volcano, in Southern Bolivia. The aims of the campaigns were to determine the local gravity anomaly. In addition, a joint GPS/microgravity network was installed for repeat measurements in the future. These dynamic data will be used to constrain the evolution of mass and density changes beneath Uturuncu. The GEF loans supplement research in the area as part of the NERC standard grant NE/G01843X/1. Both campaigns proved successful in achieving the aim of the surveys and uncertainties in the post‐processing of the data were lower than expected. The local gravity anomaly map shows several local minima, related to Quaternary stratovolcanoes, and no clear correlation to the large Neogene ignimbrite systems. Our first interpretations point to the presence of partial melt beneath the most recently active volcanoes.