Geodetic Measurements and Numerical Models of Deformation: Examples from Geothermal Fields in the Western United States

Abstract

Interferometric Synthetic Aperture Radar (InSAR) is an indispensable tool for measuring crustal deformation due to tectonic and anthropogenic processes. It provides unsurpassed spatial sampling, very good precision, and a useful observation cadence. By analyzing the temporal evolution and spatial pattern of the deformation, we can gain insight into the subsurface processes. Here, we use InSAR data acquired by the ERS-1, ERS-2, Envisat, ALOS, ALOS-2, TerraSAR-X, and TanDEM-X satellite missions to measure time-dependent deformation at a number of producing geothermal fields in the Western United States: including Raft River in Idaho, Coso and East Mesa in California, as well as Brady Hot Springs and Dixie Valley in Nevada. Although most of these sites exhibit subsidence, at least one shows transient uplift. We use the geodetic observations to constrain numerical models of the reservoir. We explore several different hypotheses for the processes driving subsidence, including poroelastic compaction and/or thermoelastic contraction.