利用GPS数据研究南北地震带北段近期地壳水平形变特征

Study of the Recent Crustal Horizontal Deformation in the Northern Segment of the North-South Seismic Belt Based on GPS Data

采用中国地震局"陆态网络"GPS基准站和流动站观测数据,利用MIT的开源软件GAMIT/GLOBK解算南北地震带北段(33°~42°N,97°~110°E),特别是六盘山地区、祁连地块、银川地堑1999年以来在欧亚框架下、以鄂尔多斯块体作为参考的GPS速度场。计算南北地震带北段5条断裂两侧50~350km范围内各站垂直/平行于断裂走向的速度投影,以及14个基准站18条基线2010年以来的长度时间序列,试图进一步估计关心区域的应力积累情况,探索断层闭锁段。结合地震活动性,认为南北地震带北段未来50年有发生M8地震的可能性;该段1900年以来的第4个M6、M7地震活跃期可能已经拉开序幕,未来2年有发生M7以上地震的可能性;祁连断裂带、海原断裂、西秦岭北缘地震带具备发生M6和M7地震的优先条件,尤其是海原断裂。

To study the characteristics of the recent crustal horizontal deformation in the northern segment of the North-South seismic belt,the GPS velocity field in the northern segment of the North-South seismic belt（33°-42°N,97°-110°E）since 1999 was computed based on the GPS data from stations of the Crustal Movement Observation Network of China using the GAMIT/GLOBK software.These findings,combined with information on the seismic activities in the study area,suggest that M ≥8.0 earthquakes will likely occur in the northern segment of the North-South seismic belt in the next 50 years;the fourth active period of earthquakes since 1900 with magnitude 6-7 may have already arrived,and in the next two years,an M 7.0 earthquake may occur;there is potential risk of M6 and M7 earthquakes in the Qilianshan,northern Xiqinling,and especially Haiyuan faults.