Full-stress inversion from focal mechanisms and borehole data at Soultz-sous-Forêts

Stress inversion is a challenging task. The data describing the stress field normally includes either direct in-situ measurements in the wellbore, or indirect data – focal mechanisms of microearthquakes in the area of interest. Joint inversion of the source mechanisms and various types of borehole data allows recovering of both principal stress directions and magnitudes, as well as accounts for the stress variations with depth as long as these variations can be described with a linear function of depth. We apply such inversion to the data from the well-studied geothermal site at Soultz-sous-Forěts, where the directions of the maximum and intermediate stress interchange with depth.