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<p>The ongoing Cenozoic collision between the Indian plate and the Eurasian plate has induced intense tectonism across the Tibetan Plateau, producing a suite of N–S-trending extensional normal faults. Internally, the plateau accommodates east–west rift systems under the combined effects of compression-driven uplift and gravitational collapse, with earthquakes dominated by extensional mechanisms. Along the Himalayan orogenic front, thrust faults governed by compressional stresses prevail, and large earthquakes are frequent. The 2025 <i>M</i><sub>w</sub>6.8 Dingri earthquake nucleated on the Dingmucuo fault in the southern segment of the Xainza–Dinggye Rift System at a focal depth of ~ 10&#xa0;km. The focal mechanism indicates normal faulting with a minor left-lateral strike-slip component. Field surveys and InSAR data reveal a ~ 30–50&#xa0;km-long surface rupture with a maximum vertical offset of 3.0&#xa0;m. Kinematic inversion reveals unilateral rupture propagation with a peak slip of 4&#xa0;m and dip angles of 50–60°. Using high-precision aftershock relocations and cluster analysis, we divide the seismogenic fault into three segments striking 140.4°, 193.7°, and 224.9°; the dip angle decreases progressively along strike, which is consistent with the trend of the Dingmucuo fault. Variations in fault geometry may have altered the rupture process, generating high-frequency radiation that intensified near-surface damage. Dynamic stress-drop analysis indicates that stress release is concentrated within the 0–10&#xa0;km depth range, whereas the 5–15&#xa0;km depth range retains unrelieved stress and hosts abundant aftershocks. Directivity effects render ground motions on the northern segment markedly greater than those on the southern segment, with stronger shaking on the hanging wall than on the footwall; the simulated maximum intensity reaches VIII. The Dingri event disrupted the stress equilibrium between the Himalayan thrust belt and the intraplateau rifts. Although the late Pleistocene slip rate of the Dingmucuo fault is &lt; 1&#xa0;mm/a, the magnitude of the actual earthquake matches its potential, underscoring that faults with low activity rates remain capable of generating significant future earthquakes.</p>

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Rupture characteristics and tectonic mechanisms of the 2025 Dingri Mw6.8 earthquake in southern Tibet

  • 期刊论文

  • 发表日期：

    2026年6月3日

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  • Zhangdi Xie

摘要

The ongoing Cenozoic collision between the Indian plate and the Eurasian plate has induced intense tectonism across the Tibetan Plateau, producing a suite of N–S-trending extensional normal faults. Internally, the plateau accommodates east–west rift systems under the combined effects of compression-driven uplift and gravitational collapse, with earthquakes dominated by extensional mechanisms. Along the Himalayan orogenic front, thrust faults governed by compressional stresses prevail, and large earthquakes are frequent. The 2025 Mw6.8 Dingri earthquake nucleated on the Dingmucuo fault in the southern segment of the Xainza–Dinggye Rift System at a focal depth of ~ 10 km. The focal mechanism indicates normal faulting with a minor left-lateral strike-slip component. Field surveys and InSAR data reveal a ~ 30–50 km-long surface rupture with a maximum vertical offset of 3.0 m. Kinematic inversion reveals unilateral rupture propagation with a peak slip of 4 m and dip angles of 50–60°. Using high-precision aftershock relocations and cluster analysis, we divide the seismogenic fault into three segments striking 140.4°, 193.7°, and 224.9°; the dip angle decreases progressively along strike, which is consistent with the trend of the Dingmucuo fault. Variations in fault geometry may have altered the rupture process, generating high-frequency radiation that intensified near-surface damage. Dynamic stress-drop analysis indicates that stress release is concentrated within the 0–10 km depth range, whereas the 5–15 km depth range retains unrelieved stress and hosts abundant aftershocks. Directivity effects render ground motions on the northern segment markedly greater than those on the southern segment, with stronger shaking on the hanging wall than on the footwall; the simulated maximum intensity reaches VIII. The Dingri event disrupted the stress equilibrium between the Himalayan thrust belt and the intraplateau rifts. Although the late Pleistocene slip rate of the Dingmucuo fault is < 1 mm/a, the magnitude of the actual earthquake matches its potential, underscoring that faults with low activity rates remain capable of generating significant future earthquakes.