GNSS约束的红河断裂带现今三维闭锁耦合程度及时空演变特征研究

Time-Space Evolution of the Current Three-Dimensional Fault Locking of the Red River Fault Zone Constrained by GNSS

为研究红河断裂带近年来活动状态的演变特征,并分析该区域地震危险性,基于1999~2007年、1999~2017年2期GNSS速度场数据,采用负位错块体模型反演红河断裂带的闭锁程度与滑动亏损空间动态分布。结果表明,红河断裂带的闭锁程度具有两端强、中间弱的特点。红河断裂带北段和南段局部断层闭锁深度为20 km,闭锁程度较高;中段为浅层闭锁,闭锁深度为5 km。在滑动亏损方面,北段为2.5~5 mm/a,积蓄能量速度较快;中段为0.4~1.8 mm/a,南段为1.5~2 mm/a,中、南两段较为平稳。在2008年以后,红河断裂带整体闭锁特点不变,南、北两段深度闭锁状态开始向中间扩散,红河断裂带整体闭锁程度加深,同时滑动亏损速率有所增加,断层北段地震风险继续增大,而断层南段活动状态变得不稳定。

In order to study the evolution characteristics of geological activity of the Red River fault zone in recent years,and analyze the seismic risk in the region,we use the GNSS velocity field data of 1999-2007 and 1999-2017.The negative dislocation-block model is used to invert fault locking and slip deficit velocity of the Red River fault zone.The results show that the locking degree of the Red River fault zone is characterized by strong ends and weak middle.The locking depth of the southern and northern segments are 20 km and the locking degree is relatively high.The locking depth of the middle segments are 5 km and the locking degree is relatively low.In terms of slip deficit,the northern segment is 2.5-5 mm/a,with a faster rate of energy accumulation.The middle segment is 0.4-1.8 mm/a,and the southern segment is 1.5-2 mm/a.The middle and southern segments are relatively stable.After 2008,the locking degree of the Red River fault zone maintained the previous characteristic.The deep locking state of the northern and southern segments began to spread to the middle,and the overall locking degree of the Red River fault zone deepened.At the same time,the slip deficit rate increased.The seismic risk of the northern segment continued to increase,while the active state of the southern segment became unstable.