Glacier unloading effects on stress redistribution above magma bodies in ice-filled volcanoes

Abstract

Climate warming is accelerating glacier thinning and altering the mechanics of ice-capped volcanoes. At Sollipulli volcano (Southern Andes), DEM differencing between 1979 and 2013 reveals up to ~300 m of surface lowering and an accelerating, non-linear trend fitted with a quadratic function. Using this relationship, Finite Element Method models were developed to simulate how progressive glacier unloading modifies crustal stresses above a shallow magma reservoir. Results show that accelerated thinning markedly reduces the minimum principal stress at the chamber roof and expands an overlying tensile domain, particularly during late-stage unloading. Magma overpressure amplifies these effects, promoting earlier tensile transitions and greater stress changes. The model reproduces key features of observed ice loss and its mechanical consequences. This study provides the first quantitative assessment of such processes in the Andes, where thick caldera-filling glaciers enhance crustal sensitivity to accelerated ice loss and associated volcanic hazards.