[S-SS07] Environmental Seismology: from deep earth to surface process

[SSS07-P12] Source parameters and tectonic implications of the 2025 Ms6.8 southern Tibetan plateau earthquake

*Ling Bai¹、Zhiwen Chen¹、Shaojun Wang¹、Sanjev Dhakal¹ (1.Institute of Tibetan Plateau Research, Chinese Academy of Sciences)

キーワード：2025 Ms6.8 southern Tibetan plateau earthquake, Source parameters, Tectonic implications

On January 7, 2025 at 09:05, a Ms 6.8 earthquake occurred in Dingri County, southern Tibetan Plateau, about 100 km north of Mount Qomolangma (i.e. the 2025 Dingri earthquake). It has a maximum intensity of IX and caused the collapse of 27,000 buildings and the death of 126 people. The earthquake occurred on a normal fault in the upper crust in the Shenzha-Dingjie rift zone of the Tethys Himalayan tectonic unit. We analyze source parameters of the 2025 Dingri earthquakes and the seismicity of the central Himalayan region based on local seismic stations we deployed in and around the source area. We also discuss the tectonic background of the earthquake based on previous studies on the plateau evolution and the geological tectonics of the region.
For the mainshock, the large amplitude seismic signal appeared about 10 s after the initial P wave arrival. The maximum rupture propagated about 30 km away from the initial rupture point. These observations are consistent with the earthquake relocations and the north-east trending surface ruptures. After the 2015 Ms8.1 Nepal earthquake, seven earthquakes of Ms>4.5 occurred around the Shenzha-Dingjie rift area with the similar normal faults. The 2025 Dingri earthquake is the largest among them. These earthquakes are all located in the central Himalayan region and indicate a strong tectonic link between the southern and northern parts of the Himalayan collision arc.