Hui Zhang

Induced seismicity is a recognized challenge in hot dry rock (HDR) geothermal development. Based on a systematic review of previous studies on induced seismicity mechanisms, characteristics, risk assessment, and mitigation measures, we compiled publicly available data from 13 HDR projects worldwide. Our statistical analysis shows that felt earthquakes occurred in 62% of the projects, and a post-injection “tailing effect” was observed in 54% of the projects. The spatial influence range of induced seismicity is typically within 2 km of the injection well, and the duration of the “Kaiser effect” varies from months to years depending on local conditions. A cross-site comparison of injection parameters suggests that the maximum wellhead pressure may be a more useful indicator than injected volume for estimating the largest possible earthquake magnitude, especially when comparing different tectonic settings. Furthermore, we examine the applicability and limitations of b-value trends, seismogenic indices, and existing maximum magnitude prediction models in seismic risk assessment. Dynamic adjustment of injection parameters based on real-time risk indicators, combined with safer injection schemes, may represent an important research direction for improving the conventional traffic light system. These findings provide a data-driven basis for site-specific safety management of HDR development.