1. A computer-implemented method for modeling deformation in subsurface strata within a geomechanical system, comprising: defining physical boundaries for the geomechanical system; acquiring one or more mechanical properties of the subsurface strata within the physical boundaries; acquiring one or more thermal properties of the subsurface strata within the physical boundaries; creating a finite element mesh representing the geomechanical system, the mesh defining a plurality of nodes representing points in space, each node having potential displacement in more than one direction, and each node being populated with at least one of each of the mechanical properties and the thermal properties; providing a computer-implemented finite element analysis program for the finite element mesh, the program solving for in situ stress at selected nodes; running the finite element analysis program a first time in order to acquire in situ stress values within the geomechanical system at selected nodes at an initial time, thereby initializing a geostatic condition of the geomechanical system; running the finite element analysis program a second time in order to acquire in situ stress values within the geomechanical system at selected nodes at a subsequent time in response to changes in at least one of the mechanical or thermal properties.