Lithospheric Equilibrium, Environmental Changes, and Potential Induced-Earthquake Risk around the Newly Impounded Baihetan Reservoir, China

The Baihetan hydropower station is the second largest worldwide. It began to store water in April 2021. We conducted a dense hybrid gravity and GNSS survey at 223 stations, obtained free-air Bouguer anomalies, inversed lithospheric density structure, calculated isostatic additional force (IAF) borne by lithosphere reservoir area. Moreover, we studied change Coulomb stress around due impoundment. main findings are following. (1) Hybrid observations significantly improved spatial resolution of field, maximum improvement reached up 150 mGal. (2) A new method for risk assessment reservoir-induced earthquakes proposed from perspective equilibrium. was found that there an IAF −30 MPa approximately 20 km upstream dam, earthquake this area warrants attention. (3) variation on Xiaojiang fault near Qiaojia depth 10 exceeded threshold inducing (0.1 bar).