新疆精河2017年6.6级地震对2018年5.4级地震的应力影响分析

Analysis of the Stress Effect of 2017 Jinghe M S6.6 Earthquake on the 2018 Jinghe M_(S)5.4 Earthquake

基于2017-08-09新疆精河6.6级地震同震破裂位错模型和区域地壳速度结构,利用粘弹性模型计算其地表位移、同震及震后应力场扰动变化,分析其对2018-10-16精河5.4级地震的应力触发关系。结果表明,精河6.6级地震造成的同震位移主要为地表垂向位移,最大位移量为84 mm,地表水平位移最大位移量为25 mm;地震引起发震断裂及其与博阿断裂交会区、库松木楔克断裂东段及分支断裂、喀什河断裂东段库仑应力增加,这些断裂靠近精河6.6级地震震中部分库仑应力增加超过10 kPa,但5~10 a尺度内的应力扰动基本为弹性响应,并未随时间显著变化。精河6.6级地震造成的精河5.4级地震震中位置同震库仑应力变化显著低于10 kPa的触发阈值,两者不存在同震或震后应力触发关系。

In order to investigate whether there is triggering relationship between the 2017-08-09 Jinghe M_(S)6.6 earthquake and the 2018-10-16 Jinghe M_(S)5.4 earthquake in Jinghe County,based on the Jinghe M_(S)6.6 earthquake co-seismic fracture dislocation model and regional crustal velocity structure,we use a viscoelastic model to calculate the surface displacement,co-seismic and post-seismic stress field disturbance of the 2017 Jinghe M_(S)6.6 earthquake.We analyze the stress triggering relationship between the M_(S)6.6 and the M_(S)5.4 earthquake.The results show that the co-seismic displacement caused by the Jinghe M_(S)6.6 earthquake is mainly surface vertical displacement,with a maximum of 84 mm.The horizontal maximum displacement is 25 mm.The earthquake causes the increase of Coulomb stress in the seismogenic fault and its intersection with Bolokenu-Aqikekuduke fault,the eastern segment and branch of Koxemqed fault,and the eastern segment of Kashgar river fault.The Coulomb stress in these areas near the epicenter of Jinghe M_(S)6.6 earthquake increases by more than 10 kPa,but the disturbance is basic elastic stress response in 5~10 a scale,without significant changes with time.The variation of co-seismic Coulomb stress in the epicenter of Jinghe M S5.4 earthquake caused by the Jinghe M S6.6 earthquake is significantly lower than the trigger threshold of 10 kPa.The comprehensive analysis shows that there is no co-seismic or post-seismic stress trigger relationship between the two earthquakes.