| 用大量地震震源机制解检验2008年汶川地震对后续地震的触发作用 |
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| 引用本文： | 盛书中,万永革,徐锡伟,程佳,杨宜海,蒋长胜,胡晓辉,杨帆.用大量地震震源机制解检验2008年汶川地震对后续地震的触发作用[J].地球物理学报,2019,62(12):4588-4603. |
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| 作者姓名： | 盛书中 万永革 徐锡伟 程佳 杨宜海 蒋长胜 胡晓辉 杨帆 |
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| 作者单位： | 1. 防灾科技学院, 河北三河 065201;2. 中国地震局地质研究所, 活动构造与火山重点实验室, 北京 100029;3. 中国地震局地壳应力研究所, 北京 100085;4. 陕西省地震局, 西安 710068;5. 中国地震局地球物理研究所, 北京 100081 |
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| 基金项目： | 国家自然科学基金项目（41704053，41674055）和河北省地震科技星火计划（DZ20170109001）联合资助. |
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| 摘 要： | 2008年汶川M_S8.0强震过去已十几年,这期间,震源区发生了大量的余震,震源周边地区发生了多次中强震.本研究利用大量震源机制解资料系统地研究汶川地震对其周边中强震及其余震触发作用,并将研究结果与先前研究结果进行了对比和分析,获得以下结论:(1)汶川地震对其周边发生的中强震存在一定的触发作用;(2)当等效摩擦系数为0.4时,由三种震源破裂模型获得的余震触发率均为65%左右(以0.01 MPa为阈值);(3)随着等效摩擦系数的增大,余震震源机制解节面上ΔCFS为正的地震数增多,反映主震触发作用增强,这与等效摩擦系数增大地震难以发生并不矛盾,而是反映等效摩擦系数增大时,断层面上正应力对ΔCFS的贡献增大,同时表明在分析库仑应力触发作用时,合理选取等效摩擦系数是至关重要的;(4)统计余震震源机制解节面上受到的库仑应力大于某一数值和小于其相反数的地震数之比时,随着统计阈值的增大,比值呈现出增大的趋势,同时比值也变得离散,该现象还有待于进一步研究.
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| 关 键 词： | 汶川地震 库仑应力变化(ΔCFS) 等效摩擦系数 余震 震源机制解 |
| 收稿时间： | 2018-04-03 |
Using a large number of focal mechanism solutions to examine the Coulomb stress triggering effect of the 2008 Wenchuan earthquake on its subsequent earthquakes |
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| SHENG ShuZhong,WAN YongGe,XU XiWei,CHENG Jia,YANG YiHai,JIANG ChangSheng,HU XiaoHui,YANG Fan.Using a large number of focal mechanism solutions to examine the Coulomb stress triggering effect of the 2008 Wenchuan earthquake on its subsequent earthquakes[J].Chinese Journal of Geophysics,2019,62(12):4588-4603. |
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| Authors: | SHENG ShuZhong WAN YongGe XU XiWei CHENG Jia YANG YiHai JIANG ChangSheng HU XiaoHui YANG Fan |
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| Institution: | 1. Institute of Disaster Prevention, Sanhe Hebei 065201, China;2. Key Laboratory of Active Tectonics and Volcano, Institute of Geology, China Earthquake Administration, Beijing 100029, China;3. Institute of Crustal Dynamics, China Earthquake Administration, Beijing 100085, China;4. Shaanxi Earthquake Agency, Xi'an 710068, China;5. Institute of Geophysics, China Earthquake Administration, Beijing 100081, China |
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| Abstract: | During the ten years after the 2008 Wenchuan MS8.0 earthquake, a large number of aftershocks occurred in the source region, and many moderate to large earthquakes occurred in the surrounding regions. Using focal mechanism solutions of these events, we systematically study the stress triggering effect of the Wenchuan earthquake, and compared our study with previous work. Results show that (1) the Wenchuan earthquake has a certain triggering to major shocks in the surrounding regions. (2) When the effective friction coefficient is 0.4, the triggering ratios of the aftershocks are all about 65% in three difference source models (with a threshold 0.01 MPa). (3) While we increase the value of the effective friction coefficient, the number of aftershocks with positive ΔCFS on its nodal plane also increases. This result is not contradictory to the fact that the earthquake occurrence is difficult with increasing effective friction, but showing the effects of the increasing normal stress on the ΔCFS values, and also reasonable choice of the effective friction coefficient is crucial in the analysis of the ΔCFS. (4) We count the number of the earthquakes of which the ΔCFS on its nodal plane is greater than a certain positive value, this value is considered as a statistical threshold value, and the number of the earthquakes of which the ΔCFS on its nodal plane is less than the inverse number, then calculate the ratios of the former to the latter. Consequently, with the increase of the threshold value, these ratios become larger and discrete. This phenomenon needs to be further studied. |
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| Keywords: | Wenchuan Earthquake Coulomb failure stress change (ΔCFS) Effective friction coefficient Aftershock Focal mechanism solution |
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