2014年新疆于田Mw7.0地震源区静态库仑应力变化和地震活动率

发布时间：2018-04-10 18:38

本文选题：于田地震 + 静态库仑应力变化　；参考：《成都理工大学》2017年硕士论文

【摘要】：2014年2月12日新疆于田Mw7.0地震源区位于巴颜喀拉块体与西昆仑块体的连接部位,东西向拉张构造区。距离2008年3月21日新疆于田Mw7.1地震震中位置约100 km。地震发生前后的静态库仑应力变化能够指示地震之间的相互触发关系、余震空间分布规律和周边活动断层的地震危险性,同时可能改变邻近区域的地震活动率。因此,我们从中国地震台网中心和国家地震数据共享中心下载新疆于田地区2009年以来震级大于ML1.0的地震事件目录,调查静态库仑应力变化和地震活动率。根据有限断层地震破裂过程模型,计算了2008年新疆于田地震产生的静态库仑应力变化,此次地震的断层面呈北偏东方向,在断层两端出现3个应力加载区,2014年2月12日新疆于田Mw7.0地震破裂面出现在库仑应力加载区,因此可以推测2008年于田地震对这次地震事件起到了触发作用。通过计算2008年于田地震和2014年于田地震在最优破裂面上产生的静态库仑应力变化,发现静态库仑应力变化与余震事件的空间分布具有明显的相关性。大多数余震事件位于应力加载区,发生在阴影区的余震事件较少。可以看出,静态应力变化能够指示余震序列可能发生的位置。2014年于田地震之后40天,在北西方向发生Mw5.2强余震。其震中位置的应力增量达到0.63 bar。通过计算2014年于田地震对周边主要活动断裂产生的库仑应力变化,发现了普鲁断裂中段、康西瓦断裂中段和贡嘎错断裂东北段上发生地震的概率加大。计算2014年2月12日新疆于田Mw7.0地震前后两个时段地震事件的最小完整性震级Mc来确定地震目录的完整性。从2009年到2014年,发生在2014年2月12日新疆于田Mw7.0地震之前的最小完整性震级Mc=2.9。震后的最小完整性震级Mc=2.0。利用这两个参数,可以计算Z值分布,用来指示地震活动率。结果表明,静态库仑应力变化与地震活动率具有较好的相关性。地震活动率较高的区域与静态库仑应力加载区相对应,如康西瓦断裂东段、贡嘎错断裂的中段和东北段等区域。
[Abstract]:The source region of the Yutian Mw7.0 earthquake in Xinjiang on February 12, 2014 is located at the junction between Bayan Kara block and West Kunlun block, and the east-west extensional tectonic area.It is about 100km from the epicenter of the Mw7.1 earthquake in Yutian, Xinjiang, on March 21, 2008.The change of static Coulomb stress before and after the earthquake can indicate the mutual triggering relationship between the earthquakes, the spatial distribution of aftershocks and the seismic risk of the active faults around the earthquake, and may change the seismic activity rate in the adjacent areas at the same time.Therefore, we download from the China Seismic Network Center and the National Seismic data sharing Center the catalogue of earthquakes with magnitude greater than ML1.0 since 2009 in Yutian region, Xinjiang, and investigate the static Coulomb stress variation and seismic activity rate.Based on the rupture process model of finite fault ground earthquake, the static Coulomb stress variation caused by the 2008 Yutian earthquake in Xinjiang is calculated. The fault plane of this earthquake is northeastward.There are three stress loading zones at the two ends of the fault, and the rupture surface of the Yutian Mw7.0 earthquake in Xinjiang on February 12, 2014 appears in the Coulomb stress loading area, so it can be speculated that the 2008 Yutian earthquake triggered the earthquake event.By calculating the static Coulomb stress variation on the optimal fracture surface of the 2008 Yutian earthquake and the 2014 Yutian earthquake, it is found that the static Coulomb stress variation has obvious correlation with the spatial distribution of aftershock events.Most aftershock events are located in the stress loading area, and the aftershock events in the shadow region are less.It can be seen that the static stress changes can indicate the possible location of the aftershock sequence. Forty days after the 2014 Yutian earthquake, a strong Mw5.2 aftershock occurred in the north-west direction.The stress increment of the epicenter is 0.63 bar.By calculating the Coulomb stress changes caused by the Yutian earthquake in 2014 to the main active faults around it, it is found that the probability of earthquakes occurring in the central segment of the Pu fault, the middle section of the Kangxiwa fault and the northeast section of the Gonggao fault is increased.The minimum integrality magnitude (Mc) of the earthquake events in two periods before and after the February 12, 2014 Mw7.0 earthquake in Yutian, Xinjiang, is calculated to determine the integrity of the earthquake catalogue.From 2009 to 2014, the smallest integrality magnitude of 2. 9 occurred before the February 12, 2014 Mw7.0 earthquake in Yutian, Xinjiang.After the earthquake, the minimum integrality magnitude is 2. 0.Using these two parameters, the Z value distribution can be calculated and used to indicate the seismic activity rate.The results show that the static Coulomb stress variation has a good correlation with the seismic activity rate.The region with high seismic activity rate corresponds to the static Coulomb stress loading area, such as the eastern section of the Kangxiwa fault, the middle section of the Gonggao fault and the northeast section, and so on.
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P315

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