Analysis of Co-seismic and Pre-earthquake GNSS Deformation Characteristics of Xizang Dingri MS6.8 Earthquake
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摘要: 北京时间2025年1月7日9点5分，在我国西藏定日县发生了6.8级地震。利用震中周边 GNSS连续观测数据反演获取同震位移场，结果表明，距离震中最近的测站为XZZF站，其同震位移量最大，南北向达到−17.14 mm，东西向达到−41.62 mm，基于震中周边3个站点的同震位移数据特征分析，此次地震呈现出典型的正断型地震运动学特征；对GNSS站间基线时间序列及区域应变时间序列的系统性研究结果显示，登么错断裂（又称丁木错断裂）带处于显著的拉张运动状态；震前 GNSS 动态应变场的分析结果表明，该区域的面应变由挤压逐渐变为拉张趋势，量值较小，且始终处在拉张应变高值区边缘；块体模型计算得到申扎-定结裂谷的左旋滑动速率为（3.2±0.5）mm/a，伸展速率为（1.4±0.6）mm/a，GNSS剖面计算得到发震断层登么错的拉张滑动速率为(1.58±0.6) mm/a，左旋滑动速率为(1.49±0.7) mm/a，裂谷南段的运动速率相对于整个裂谷运动速率较小，且处于应变高值区边缘，未来仍有发生强震的可能。Abstract: At 09:05 local time on January 7, 2025, a magnitude 6.8 earthquake occurred in Dingri County, Tibet, China. Inversion of co-seismic displacement fields using continuous GNSS observations from stations near the epicenter reveals that the station closest to the epicenter, XZZF, recorded the largest co-seismic displacement, with −17.14 mm in the north–south direction and −41.62 mm in the east–west direction. Analysis of co-seismic displacement data from three GNSS stations surrounding the epicenter indicates that the earthquake exhibits kinematic features characteristic of a typical normal faulting event. A comprehensive study of GNSS baseline time series and regional strain time series shows that the Dingmucuo fault zone is currently undergoing significant extensional deformation. Pre-seismic GNSS dynamic strain field analysis suggests that the regional areal strain transitioned from compressive to tensile, although the magnitude of this change remained small and the region was consistently located at the periphery of a high tensile strain zone. Block model calculations estimate the left-lateral slip rate of the Shenzha–Dingjie Rift to be (3.2 ± 0.5) mm/year, and the extensional (tensional) slip rate to be (1.4 ± 0.6) mm/year. GNSS profile analysis of the source fault, the Dingmucuo fault, yields an extensional slip rate of (1.58 ± 0.6)mm/year and a left-lateral slip rate of (1.49 ± 0.7)mm/year. Compared to the entire rift system, the southern segment of the Shenzha–Dingjie Rift exhibits relatively lower movement rates. However, the continued accumulation of regional strain suggests a persistent potential for future large-magnitude earthquakes.
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Key words:
- Dingri earthquake /
- GNSS /
- Co-seismic /
- Strain /
- Slip rate
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图 5 青藏高原多期速度场结果
Figure 5. Measured multi-period velocities on the Qinghai-Tibet plateau
图 8 输入GNSS速度场及解算残差
Figure 8. Distribution of GNSS velocity field and simulation residuals of GNSS
图 10 登么错断裂带GNSS剖面结果
Figure 10. The slip rates along the Dingmucuo fault by GNSS measurement
表 1 GNSS测站的同震位移量（单位：毫米）
Table 1. The co-seismic displacement measured from the GNSS stations （Unit: mm）
测站名称 东西向（东为正） 南北向（北为正） XZAR −6.51 0.04 XZRK 10.01 6.17 XZZF −41.62 −17.14 
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