Enigmatic large-scale (>150 km wide) ground deformation in southern Bolivia has been ongoing for more than 50 year. Concurrent changes in gravity recorded between 2010 and 2018 imply minor changes in subsurface density in the absence of significant mass changes. Numerical modeling of the gravity changes and concurrent InSAR LOS displacements gives annual bulk density changes of 0.002 kg m⁻³ in the Altiplano-Puna Magma Body (APMB) and −0.03 kg m⁻³ in a vertical bulge-column ensemble beneath Uturuncu volcano. We propose that the transcrustal migration of fluids from the APMB to shallower crustal levels by compressible flow is the source of ground deformation. Localized ground subsidence south of Uturuncu can be best explained by a density decrease of 20 ± 5 kg m⁻³ between 2011 and 2013 in a hydrothermal reservoir. Our findings contribute to the growing recognition of transcrustal fluid migration as a source of volcanic unrest.

中文翻译：

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经壳可压缩流体流动解释了高原-普纳重力和变形异常

玻利维亚南部神秘的大规模（>150 公里宽）地面变形已经持续了 50 多年。2010 年至 2018 年间记录的重力同时变化意味着在没有显着质量变化的情况下，地下密度发生了微小变化。重力变化和同时 InSAR LOS 位移的数值模拟给出了 Altiplano-Puna 岩浆体 (APMB) 中的年体积密度变化为 0.002 kg m ^{-3和 Uturuncu 火山下方的垂直凸起柱系综中 -0.03 kg m -3}。我们提出流体通过可压缩流动从 APMB 向较浅地壳水平的跨地壳迁移是地面变形的来源。Uturuncu 以南的局部地面沉降可以用 20 ± 5 kg m ^{-3的密度下降来最好地解释}2011 年至 2013 年间在一个热液储层中。我们的研究结果有助于越来越多地认识到跨地壳流体迁移是火山动荡的根源。