Seismic hazard assessment of Henggang reservoir based on probabilistic statistical methods

Reservoir-induced seismicity refers to potential seismic hazards that may be triggered by reservoir impoundment or water level fluctuations. Risk assessments are crucial for safety and the prevention and mitigation of regional disaster. This paper outlines research advances on reservoir-induced seismicity domestically and internationally and highlights the current shortcomings in understanding its causes, triggering conditions, and mechanisms. These gaps may affect the validity of risk assessment results for reservoir-induced seismicity. To address this, after summarizing the strengths and weaknesses of qualitative, semi-quantitative, and comprehensive risk assessment methods, this study considers the constructed Henggang reservoir as an example. Based on probabilistic statistical methods combined with seven reservoir-induced seismicity factors, this study analyzed the seismic risk and identified areas for improvement in the probabilistic statistical approach. The results indicate that the probabilities of the reservoir inducing strong, moderate, weak, and micro earthquakes were all relatively low, which aligns with over 20 years of actual monitoring data from regional and near-field seismic networks. Furthermore, by analyzing global patterns of seismic frequency at different time intervals after reservoir impoundment and seismic monitoring data from the reservoir’s near-field area over the past two decades, the credibility of the risk assessment results for the Henggang reservoir based on probabilistic statistical methods was further validated. These findings serve as a reference for the seismic risk assessment of small- and medium-sized reservoirs while also pointing to ways to enhance the accuracy of statistical prediction models.