Numerical models of caldera deformation: Effects of multiphase andmulticomponent hydrothermal fluid flow

摘要

Ground surface displacement (GSD) in large calderas is often interpreted as resultingfrom magma intrusion at depth. Recent advances in geodetic measurements of GSD,notably interferometric synthetic aperture radar, reveal complex and multifaceteddeformation patterns that often require complex source models to explain the observedGSD. Although hydrothermal fluids have been discussed as a possible deformation agent,very few quantitative studies addressing the effects of multiphase flow on crustalmechanics have been attempted. Recent increases in the power and availability ofcomputing resources allow robust quantitative assessment of the complex time-variantthermal interplay between aqueous fluid flow and crustal deformation. We carry outnumerical simulations of multiphase (liquid-gas), multicomponent (H2O–0O2)hydrothermal fluid flow and poroelastic deformation using a range of realistic physicalparameters and processes. Hydrothermal fluid injection, circulation, and gas formation cangenerate complex, temporally and spatially varying patterns of GSD, with deformationrates, magnitudes, and geometries (including subsidence) similar to those observed inseveral large calderas. The potential for both rapid and gradual deformation resulting frommagma-derived fluids suggests that hydrothermal fluid circulation may help explaindeformation episodes at calderas that have not culminated in magmatic eruption.