Preliminary design of a traffic light system for risk management of earthquakes induced by hot dry rock fracturing

Hot dry rock (HDR) is a strategic clean energy resource with considerable advantages, including abundant reserves, stable power output, and renewability. However, induced seismicity remains a primary challenge in HDR development and represents a critical bottleneck, leading to the termination or postponement of several international projects. This study systematically reviews the composition, typical case studies, and existing problems of current traffic light systems (TLS) for seismic risk mitigation during HDR hydraulic stimulation. Based on the principles of selecting parameters that directly relate to seismogenesis control, are easily measurable, and facilitate systematic management, we have proposed fundamental criteria for determining TLS decision parameters and threshold settings. Subsequently, we developed an enhanced TLS framework incorporating six key parameters, namely, earthquake magnitude, b-value, peak ground velocity (PGV), injected fluid volume, injection rate, and wellhead injection pressure. We identified the major challenges facing TLS implementation and suggested future research directions, aiming to provide references for induced seismicity risk management in HDR, shale gas, and other energy sectors involving hydraulic fracturing, supporting national strategic initiatives for deep-resource exploitation.