Fault Stability Assessment in Tectonically Active Geothermal Fields Through Integrated Stress Analysis

The Tulu Moye geothermal field in the actively deforming Main Ethiopian Rift presents substantial potential for renewable energy production, where interactions between fault systems, hydrothermal fluids, and tectonic activity require careful management for sustainable development. Here we present a first-order assessment of fault stability and reactivation risks under current stress conditions to establish baseline conditions for future geothermal operations. By combining stress inversion of earthquake focal mechanisms with structural mapping, we assess fault reactivation potential through slip tendency, dilation tendency, and fracture susceptibility analyses. We evaluate critical pore pressures and stress magnitudes required for rock failure using Monte Carlo simulations to quantify uncertainties in our geomechanical parameters. Our results indicate that several faults are critically stressed, with a modest pore pressure increase (3–5 MPa) potentially triggering fault slip and induced seismicity at 2 km depth. These findings align with observed microseismicity patterns linked to hydrothermal fluid flow, which enhances reservoir permeability but increases fault reactivation risks. Our static stress analysis provides an essential baseline framework for assessing fault stability and managing risks in geothermal systems in tectonically active regions.