北天山西段中强地震应力触发作用初步研究

PRIMARY RESEARCH ON STRESS TRIGGERING OF MID-STRONG EARTHQUAKES IN THE WESTERN PART OF NORTHERN TIANSHAN MOUNTAINS

计算了新疆北天山西段1944年以来部分5级以上地震产生的静态库仑破裂应力变化(ΔCFS),分析该区先发生的中强震产生的累加库仑应力变化以及单个中强地震对后续地震的触发作用。研究中依据静态库仑破裂应力变化的空间分布确定后续地震活动的可能增强区范围,应用累积贝尼奥夫应变研究增强区内中等地震活动的加速矩释放特征,定量论证中强震产生的库仑应力变化对后续地震产生的影响的可靠性。结果表明,北天山西段多数中强震产生的ΔCFS有利于其邻区后续中强震的发生,其中正ΔCFS区是后续中强地震的可能发生地点,该区中强震产生的库仑应力变化作用的时空影响范围分别为几天至几十年1、00 km范围内,这为未来地震趋势判定提供了依据。

The article calculates the static Coulomb failure stress change（△CFS） of some Ms≥5 earthquakes since 1944 in the western part of Northern Tianshan mountain, in Xinjiang, and analyzes the triggering on the following mid-strong earthquakes from accumulative △CFS of previous mid-strong earthquakes and from the single mid-strong earthquakes. According to the spatial distribution of static △CFS, the article defines the possible active region of the following earthquake activity, and analyzes accelerating moment release character of medium earthquake activity in the active region with accumulative Benioff strain method, and proves the reliability of the action on the following earthquakes from △CFS of mid-strong earthquakes. The conclusion shows that △CFS from most mid-strong earthquakes in the western part of Northern Tianshan mountains encourage the following ones around its region, and positive △CFS region is possible risk region. The temporal and spatial range of Coulomb stress change from mid-strong earthquakes in the region, is respectively several days to tens of years, and within 100 km, which offers the criterion of future seismic trend.