新疆乌什7.1级地震前GNSS变形特征分析

Deformation characteristics before the M 7.1 earthquake in Wushi,Xinjiang,from GNSS observation data

2024年1月23日新疆乌什发生7.1级地震。为了研究震前GNSS变形特征,通过对比分析GNSS基线时间序列结果和区域应变结果,发现迈丹断裂带东西两段的地壳运动有所差异,东段的运动较强,乌什地震即发生在断裂带东段;利用4期速度场结果,计算得到动态应变场变化,从NS向应变场结果可以看出该区域的应变量值持续增加,应变持续在积累状态,从长期背景场可以看出7.1级地震发生在应变高值区的边缘;发震断层东西两侧的挤压滑动速率存在明显差异,西侧为(1.0±0.35)mm/a,东侧为(4.1±0.51)mm/a,且东侧的闭锁程度较高。研究认为迈丹断裂带两侧运动差异明显,乌什7.1级地震发生在滑动速率较高的东段,且该区域处于应变高值区的边缘。

On January 23,2024,an M 7.1 earthquake occurred in Wushi,Xinjiang.The baseline and regional strain time series from global navigation satellite system observation data were compared in this paper to explore the characteristics of regional crustal deformation before the earthquake.Results show differences in the crustal movements of the east and west segments of the Maidan fault and the strong movement of the east section,where the Wushi earthquake occurred.Dynamic GNSS strain field variations were calculated based on the four periods of velocity field results.The results of the NS-trending strain field show the continuous increase in strain value in the region and the continuous accumulation of the strain.The long-term background strain field revealed that the M 7.1 earthquake occurred at the edge of the region with high strain values.Differences in the slip rates were observed between the east and west segments of the Maidan fault,with the west side being(1.0±0.35)mm/a,the east side being(4.1±0.51)mm/a,and the east side demonstrating a high degree of locking.Therefore,the movement difference between the two sides of the Maidan fault is evident,and the M 7.1 earthquake occurs in the eastern segment with high slip rates,which is at the edge of the high strain value region.