Foreshock activity is a key consideration in traffic-light protocol (TLP) to mitigate seismic risk from injection-induced earthquakes (IIEs). However, the seismogenic processes of IIE foreshocks remain poorly understood. Using an enhanced western Canada catalog (2014-2024), we analyzed 77 IIE sequences to statistically delineate foreshock patterns before local magnitude (ML) ≥ 3 mainshocks. We found that 92% are preceded by foreshocks and that foreshock productivity and spatiotemporal patterns reflect the interplay among fluid injection, the seismogenic index, and the fault stress state. Sequence-specific analyses elucidate three nucleation models: fluid-driven preslip with weakened source asperity, fluid-driven preslip with intact source asperity, and fluid-driven cascade, highlighting the central role of fluids in enabling aseismic slip and interevent stress transfer before mainshock rupture. These results imply that IIE monitoring strategies should be spatially conditioned according to foreshock productivity.
Bei Wang, H. Kao, Hongyu Yu et al.· Science· 0 citations
Normal faults in southern Tibet have long suffered from limited ground‐based seismic and geodetic observations, constraining our understanding of both interseismic and coseismic processes and their interactions. The 2025 Mw 7.1 Dingri earthquake provides an opportunity to address these gaps. Here, we integrate interseismic slip deficit rate inversion, finite‐fault slip analyses, and 3D dynamic rupture simulations constrained by geodetic and seismic data to investigate fault behavior. The earthquake ruptured two asperities, with a shallow slip gap located above the hypocentral region, and exhibited a slow initiation followed by rapid strain release. A fault bend may have arrested the southward rupture, while the northward termination appears to have been controlled by a low slip deficit rate barrier. The shallow slip gap above the hypocenter may represent a high‐strength segment requiring elevated fracture energy for rupture initiation, resulting in the relatively slow rupture onset during the event. These results indicate that geometric complexity and heterogeneity of on‐fault stress and strength jointly governed the normal faulting. In addition, we quantified seismic moment accumulation rates on 132 normal faults in southern Tibet, finding that the accumulated moments over 500 years correspond to earthquakes of Mw 5.3–7.2. However, geometric and stress‐strength heterogeneities may reduce the likelihood of large cascading ruptures compared to large block‐bounding strike‐slip and thrust faults. Overall, our findings highlight rupture complexities of the Dingri earthquake, while underscoring substantial seismic hazards posed by rift systems in southern Tibet.
Haicheng Xiong, Yanchuan Li, Xinjan Shan et al.· Journal of Geophysical Resea...· 0 citations
