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JOURNAL OF GEOPHYSICAL RESEARCH,
VOL. 112,
B02206,
doi:10.1029/2006JB004689,
2007
Hydrothermal fluid flow and deformation in large calderas: Inferences from numerical simulations
Shaul Hurwitz
U.S. Geological Survey, Menlo Park, California, USA
Lizet B. Christiansen
U.S. Geological Survey, Menlo Park, California, USA
Paul A. Hsieh
U.S. Geological Survey, Menlo Park, California, USA
Abstract
Inflation and deflation of large calderas is traditionally interpreted as being induced by volume change of a discrete source
embedded in an elastic or viscoelastic half-space, though it has also been suggested that hydrothermal fluids may play a role.
To test the latter hypothesis, we carry out numerical simulations of hydrothermal fluid flow and poroelastic deformation in
calderas by coupling two numerical codes: (1) TOUGH2 [Pruess et al., 1999], which simulates flow in porous or fractured media,
and (2) BIOT2 [Hsieh, 1996], which simulates fluid flow and deformation in a linearly elastic porous medium. In the simulations,
high-temperature water (350°C) is injected at variable rates into a cylinder (radius 50 km, height 3–5 km). A sensitivity
analysis indicates that small differences in the values of permeability and its anisotropy, the depth and rate of hydrothermal
injection, and the values of the shear modulus may lead to significant variations in the magnitude, rate, and geometry of
ground surface displacement, or uplift. Some of the simulated uplift rates are similar to observed uplift rates in large calderas,
suggesting that the injection of aqueous fluids into the shallow crust may explain some of the deformation observed in calderas.
Received 10
September
2006;
accepted 17
October
2006;
published 24
February
2007.
Keywords: numerical simulation;
caldera;
hydrothermal;
deformation;
ground surface displacement;
poroelastic.
Index Terms: 8424 Volcanology: Hydrothermal systems (0450, 1034, 3017, 3616, 4832, 8135); 8440 Volcanology: Calderas; 8045 Structural Geology: Role of fluids; 0560 Computational Geophysics: Numerical solutions (4255); 1829 Hydrology: Groundwater hydrology.
Read Full Article (file size: 719483 bytes) Cited by
Citation: Hurwitz, S., L. B. Christiansen, and P. A. Hsieh
(2007),
Hydrothermal fluid flow and deformation in large calderas: Inferences from numerical simulations,
J. Geophys. Res.,
112,
B02206,
doi:10.1029/2006JB004689.
This paper is not subject to U.S. copyright. Published in 2007 by the
American Geophysical Union.
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