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Sequence Characteristics and Seismogenic Structure of the 2025 Xizang Dingri M6.8 Earthquake

Description: 

In this study we use continuous waveform data and seismic phase reports from the China Earthquake Networks Center to detect and supplement the sequence of the January 7, 2025, M 6.8 Xizang Dingri earthquake using deep learning methods. After relocating the entire sequence by the double-difference relocation method, we find that the sequence occurred on the Dengmocuo Fault, located in the Shenzha-Dingjie Rift. The sequence extends in a north-south direction, with an aftershock zone approximately 100 km long and 40 km wide. The depth of the earthquakes mainly ranges from 3 to 30 km, gradually becoming shallower from north to south, while the fault plane is nearly vertical, slightly inclined to the northwest. The foreshock sequence started ten days before the mainshock and showed a migration pattern towards the mainshock epicenter, with the migration speed accelerating to about 3 km/h one hour before the mainshock. It is hypothesized that the foreshock sequence have occurred on a blind minor conjugate fault, triggering the mainshock. We have also calculated focal mechanism solutions using polarity data (M3-4), local seismic waveform fitting (M>4) and W phases (mainshock). The dominant solutions are normal faulting, consistent with the tectonic setting.

The rapid reported magnitude of the mainshock was M6.8, lower than the moment magnitude 7.1, presenting a rare case for earthquakes in Chinese mainland. We compare the Ms and Mw for 260 earthquakes since 2013 and find a clear linear relationship.There displays a regional distribution of the difference between surface-wave and moment magnitude. Most earthquakes within the Qinghai-Xizang plateau have larger Ms than Mw, while some earthquakes along the margin of plateau and the Tarim basin show the opposite relationship. Our study provide scientific insights into the earthquake preparation process and mechanism of the 2025 Dingri earthquake, and offer valuable references for understanding the deformation mechanism and seismic hazard of the Qinghai-Xizang Plateau.

Session: Late-breaking on Recent and Future Large Earthquakes [Poster]

Type: Poster

Date: 4/15/2025

Presentation Time: 08:00 AM (local time)

Presenting Author: Hongfeng

Student Presenter: No

Invited Presentation: 

Poster Number: 147

Authors