Measuring and Modeling Deformation at the Utah FORGE site 2018 through 2024

This report describes research activities between August 16th, 2018 and July 30th, 2024 under a Subaward Agreement between the University of Utah and the University of Wisconsin System. The goals of the research activities are to conduct: InSAR analysis (Subtask 3.7.3) and Ground Surface Deformation Modeling (Subtask 3.4.4). Interferometric Synthetic Aperture Radar (InSAR) data have been obtained from two satellite missions, combined pair-wise into interferograms to assess ground deformation. The results are registered (?geo-coded?) into a cartographic map projection and published on the Geothermal Data Repository. Time series of displacement inferred from InSAR data are compared with those measured by GPS surveying. The InSAR data analyzed here do not show any measurable deformation in the area immediately surrounding the FORGE wells. Nor do the time series of vertical displacement measured by GPS show any signals that would reject the null hypothesis of no internal deformation with 95 percent confidence. No vertical surface displacement that could be measurable by InSAR or GPS is expected from the stimulation experiments conducted at the Utah FORGE site in 2023 or 2024. The expected vertical displacement at the Earth's surface is less than 1 millimeter, based on modeling using an analytic solution (Mogi). Hydromechanical modeling in a poroelastic medium conducted using the finite-element method also indicates vertical surface displacements smaller than 1 millimeter in magnitude. In other words, the magnitude of the deformation produced by injection experiments is too small to be measured by InSAR or GPS. A seismic event with magnitude M ~ 4, however, would likely produce measurable deformation, depending on depth and focal mechanism.