基于GPS资料研究红河断裂带现今闭锁程度与地震危险性

Study on Present-Day Locking and Seismic Hazard of the Red River Fault Zone Based on GPS Data

基于2009~2015年中国大陆GPS水平速度场数据,采用DEFNODE负位错反演程序计算红河断裂带的断层闭锁程度和滑动亏损速率特征,并结合小震精定位结果分析该断裂带的强震危险性。结果表明,GPS水平观测值与模型值的拟合结果较好,小震分布与闭锁程度结果存在一定的相关性,红河断裂的中段北部(南涧-墨江)基本完全闭锁,断层的滑动亏损速率也相对较大,该段落具有发生较大地震的可能性;红河断裂带其余段落闭锁程度较弱,尤其是断裂带的南段,在2~5km深度处基本由闭锁状态转化为蠕滑状态,断层的滑动亏损速率也相应很小,该段发生较大地震的可能性较小。

By using the GPS horizontal velocity field of 2009-2015 and the negative dislocation model of DEFNODE,we invert for fault locking and fault slip deficit of the Red river fault zone,and analyze the potential seismic danger,combining with the results of precision positioning of small earthquakes.The results show that the fitting results of GPS horizontal observation value and the simulated value are good,and there is also a certain correlation between the distribution of minor earthquakes and the degree of fault locking.The inversion results show that the middle section of the Red river fault is different from the south to north,and that the northern part is basically completely locked.The fault slip deficit rate is relatively large,which has the potential danger of a larger earthquake,and the degree of locking of the southern fault is much weaker.The locking degree of other sections of the Red river fault are also much weaker,and there are no strong blocking states in these sections,especially in the southern section of the fault zone.The fracture is basically transformed from the locking state to the creep state at 2-5 km depth,the fault slip deficit rate is relatively small,and the possibility of larger earthquakes in this section is much smaller.