2014 年于田MS 7. 3 地震产生的静态库仑应力变化及对周边断层的影响

The static stress triggering effects related with the Yutian MS 7. 3 earthquake

摘要:

计算了2008 年以来于田地区4 次MS5. 5 以上地震产生的同震静态库仑破裂应力场变化，分析它们之间的应力触发效应、4 次地震产生的应力变化与余震分布的关系及其对周边主要断层的影响。结果表明，2011 年MS5. 5、2014 年MS7. 3 地震均处于之前地震产生的库仑破裂应力增加区，增加值分别为0. 004、0. 021MPa，说明这两次地震明显受到之前强震触发作用的影响;而2012 年MS6. 2 地震位于之前地震产生的应力影区内，对其发生有延缓作用。此次MS7. 3 地震产生的库仑破裂应力场图像与目前余震空间分布特征较为吻合;但主震破裂面上部分应力增强区几乎没有余震发生，这些地区未来存在发生强余震的可能。距此次震中最近的贡嘎错断裂中段上不同断层段库仑应力扰动值变化很大，计算结果可能会受有限断层震源模型的一定影响，依然存在较强的地震危险性。此外，贡嘎错断裂东北段、普鲁断裂中西段及龙木错-邦达错断裂带西段受2008 年以来地震的累积库仑应力增加的影响也较为明显，其应力扰动最大值均超过0. 002MPa，同样存在一定地震危险性。

Abstract:

This paper calculates the static coulomb stress changes generated by 4 earthquakes in the Yutian area during 2008 ～ 2014 separately，then discusses triggering influence among them， their accumulated coulomb stress changes and their influence on nearby faults． The results indicate that the MS5. 5 earthquake in 2011 and the MS7. 3 earthquake in 2014 are both in the regions where the coulomb stress change is positive，the stress changes are 0. 004MPa and 0. 021MPa respectively． It means they were triggered by the prior earthquakes． The MS 6. 2 earthquake in 2012 occurred in the place where the coulomb stress change is negative． It is postponed by the prior earthquakes． The coulomb stress change image of the MS7. 3 earthquake in 2014 is in accord with aftershocks (ML≥3. 0) distribution，but some regions on the fault where the coulomb stress change is positive have few aftershocks． Strong aftershocks may occur at these districts in future． In addition，this paper calculates the coulomb stress change on faults nearby， and finds that the coulomb stress changes of different elements in GGC fault are very different． It must get strong triggered-influence though the result may be influenced by the input finite fault model，so it still has a large earthquake-risk． The GGN，PLC，PLW and LBW faults are also triggered by the 4 earthquakes occurred during 2008 ～ 2014，their maximum of coulomb stress change all exceed 0. 002MPa，so they also have strong earthquake-hazard．