Aug 2026· Journal of Geophysical Research - Solid Earth· Vol 131· 0 citations· 63 references
Abstract
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.
The 2025 Mw 7.1 Dingri earthquake provides a rare opportunity to investigate the dynamic rupture behavior of a normal fault within the South Tibetan rift system. In this study, we perform three-dimensional (3D) dynamic rupture simulations using the spectral element method to investigate the complex rupture process along the Dingmucuo fault. Our model incorporates a 3D curved fault with the initial slip distribution parameterized via a Bayesian von Karman approach. The simulation successfully reproduces the observed Interferometric Synthetic Aperture Radar coseismic deformation, capturing a predominantly unilateral northward-propagating rupture with a rupture duration of ∼25 s. We find that an asymmetric initial stress distribution controls rupture directivity, arresting brief southward propagation. Additionally, the geometric bend in the northwestern segment acts as a critical geometric barrier, inducing localized stress concentrations where slip rate reaches ∼1.0 m/s. These simulated dynamic processes are spatially consistent with the observed localized surface ruptures and the heterogeneous distribution of aftershock clusters. Our findings highlight the profound impact of complex fault geometry and initial stress heterogeneity on the dynamic evolution of normal-faulting earthquakes, with implications for seismic hazard assessment in the Shenzha-Dingjie rift.
Zhangdi Xie· Seismological Research Lette...· 0 citations
The 1973 MS7.6 Luhuo earthquake is the most representative strike-slip event in the Xianshuihe fault zone, yet published source models differ markedly, and the mechanism that arrested its rupture near Renda remains poorly understood. Using spectral-element dynamic rupture simulations with a nonplanar fault geometry, three-dimensional velocity model, and depth-dependent initial stress field, we test whether fault geometry or inherited stress heterogeneity controlled the termination. Our results show that N75° W is the optimal maximum principal stress orientation, yielding surface offsets, a bilateral rupture mode, and an intensity pattern consistent with observations. Fault geometry alone cannot explain the termination: continuous and dipping faults rupture completely, and a 1 km stepover at Renda blocks the rupture jump yet leaves minor slip on the secondary fault. Introducing the 1923 Daofu earthquake stress change as a low-stress barrier instead terminates rupture near Renda, and simulated magnitude, offsets, and intensity then agree with observations. A compliant damage zone raises coseismic slip and lowers the moment magnitude while contracting the meizoseismal zone, whereas topography barely alters the rupture but appreciably modulates ground motion. These findings demonstrate that inherited stress heterogeneity, rather than fault geometry, can be the primary control on rupture arrest and can inform seismic hazard assessment for the Sichuan-Yunnan fault system.
The 2024 Mw 7.3 Hualien earthquake represents a significant seismic event in a highly complex tectonic setting, providing a critical opportunity to constrain complex fault geometries and evaluate stress triggering mechanisms. We compiled a high-resolution aftershock catalog of 23,748 events from continuous seismic waveforms recorded over three months. This catalog systematically documents the spatiotemporal evolution of the 2 April 2024 Mw 7.3 Hualien mainshock and its aftershocks. The aftershock distribution outlines a conjugate fault system composed of the east-dipping Longitudinal Valley fault and the west-dipping Central Range fault, with clear depth-dependent variations in geometry. The seismicity front expanded as a logarithmic function of time, consistent with afterslip-driven migration of the Hualien earthquake sequence. The aftershocks predominantly occurred around and outside of the high-slip periphery, consistent with stress reduction within high-slip areas and stress concentration at the periphery and gradient zones of the high-slip area. Coulomb stress calculations further suggest that static stress transfer from the mainshock contributed to the occurrence of several major aftershocks. These results highlight the role of stress interactions in controlling aftershock distribution and provide constraints on postseismic hazard assessment in eastern Taiwan.
Ling-Xia Gao, Li-Hua Fang, Yi-Jian Zhou et al.· Seismological Research Lette...· 0 citations
During an earthquake a dynamic rupture propagates, causing fractures and permanent damage that modify the mechanical properties of the fault and its surroundings. Reciprocally, the energy dissipated by the mechanical transformation of the fault rock has a direct feedback on the dynamics of the seismic rupture. We reproduce and image these co‐seismic damage processes with sub‐microsecond time resolution through dynamic loading experiments on confined Westerly granite samples. Using synchrotron X‐ray imaging and ultra‐high‐speed cameras, we observed that dynamic compression with confinement produces shear faults and a localized granulation of the rock, known as gouge, before significant slip occurs. This fragmentation process begins with volumetric damage, followed by shear deformation less than 5 microseconds later. Our results indicate that gouge formation is initiated by the dynamic rupture itself, which reduces the strength of a fault prior to other weakening mechanisms that may occur during the earthquake slip.
A. Vishnu, M. Doan, J. Hollingsworth et al.· Geophysical Research Letters· 0 citations
