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[1]吴微微,梁明剑,龙 锋,等.青川断裂及邻区现今地震活动性研究[J].地震研究,2023,46(02):188-203.[doi:10.20015/j.cnki.ISSN1000-0666.2023.0035 ]
　WU Weiwei,LIANG Mingjian,LONG Feng,et al.Analysis of the Present-day Activity of the Qingchuan Fault and Its Vicinity[J].Journal of Seismological Research,2023,46(02):188-203.[doi:10.20015/j.cnki.ISSN1000-0666.2023.0035 ]
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青川断裂及邻区现今地震活动性研究(PDF/HTML)

《地震研究》[ISSN:1000-0666/CN:53-1062/P]

卷:
46
期数:
2023年02期
页码:
188-203
栏目:
出版日期:
2023-03-10

文章信息/Info

Title:
Analysis of the Present-day Activity of the Qingchuan Fault and Its Vicinity
作者:
吴微微; 梁明剑; 龙 锋; 苏金蓉; 陈学芬
(四川省地震局,四川 成都 610041)
Author(s):
WU Weiwei; LIANG Mingjian; LONG Feng; SU Jinrong; CHEN Xuefen
(Sichuan Earthquake Agency,Chengdu 610041,Sichuan,China)
关键词:
青川断裂及邻区;  汶川地震;  震源机制解;  应力降;  速度结构;  地震活动性
Keywords:
the Qingchuan fault and its vicinity;  the Wenchuan MS8.0 earthquake;  focal mechanism;  stress drop;  velocity structure;  earthquake activity
分类号:
DOI:
10.20015/j.cnki.ISSN1000-0666.2023.0035
摘要:
近年来,青川断裂及邻区多次发生4.0级以上地震,为进一步研究该区现今地震活动性,结合现场地震地质调查和无人机摄影方法测绘构造地貌,揭示青川断裂的构造变形信息; 采用CAP方法反演2008年5月17日至2021年12月31日研究区32次MW≥4.0地震的震源机制解,进一步讨论断裂的构造变形特征; 使用ω2模型拟合震源谱方法获得研究区十年尺度的应力降动态演化,分析3次强震前后研究区的应力调整过程; 通过三维P波速度结构反演,探讨研究区深部孕震背景; 最后综合地质学和地震学研究结果分析青川断裂及邻区的现今活动性。结果表明:①地震地质调查和震源机制解的结果均反映青川断裂的运动性质为走滑兼挤压。②2008年汶川8.0级和2013年芦山7.0级强震前、后,研究区的应力水平在一段时间内呈现出升高-回落的调整过程。③体波层析成像的结果显示研究区的地壳浅层高低速异常表现以龙门山断裂带为分界线的空间分布特征。④青川断裂具有潜在地震发生的构造背景与能力,但目前该断裂及邻区的地震活动正处于强震序列衰减阶段,M4.0以上地震活动呈逐渐减弱的趋势,高应力降地震事件明显减少,区域整体应力水平较低。
Abstract:
In recent years,earthquakes(M≥4.0)have been repeatedly occurring on the Qingchuan fault and in its adjacent region. Firstly,we conduct a geological investigation and carry out a surveying and mapping of landforms area by the unmanned aviation vehicle in the study in order to obtain the tectonic deformation of the Qingchuan fault. Secondly,we use the cut-and-paste method to invert the focal mechanisms of 32 earthquakes(MW≥4.0)occurring during May 17-December 31,2008 in the study area,and further study the tectonic features of the Qingchuan fault. Thirdly,we use the ω2 model to fit the source spectra to obtain the dynamic evolution of the stress drop in 10-year span in the study area. Then we analyze the stress variation before and after the 2008 Wenchuan earthquake,the 2013 Lushan earthquake,the 2017 Jiuzhaigou earthquake. Fourthly,we invert the P-wave velocity structure in the study area to discuss the tectonic settings for the earthquake genesis in the deep. Finally,on the basis of the above the geological and seismological results we analyze the resent-day activity of the Qingchuan fault. We find that:①The geological survey and the focal mechanism solution show that movement property of the Qingchuan fault is mainly strike-slip,with a certain compressive component. ②Before and after the 2008 Wenchuan earthquake and the 2013 Lushan earthquake,the stress in the study area experienced a rise-fall period. ③Spatially,the body-wave tomography shows that the high-speed anomaly and low-speed anomaly in the shallow Crust are divided by the Longmenshan fault. ④The Qingchuan fault is an earthquake-prone structure because of its tectonic settings. So far,the strong-earthquake activity is in the weakening period; the seismicity(M≥4.0)takes on a trend of gradual attenuation. High stress-drop events are significantly lessening and the overall stress level in the study area is relatively low.

参考文献/References:

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备注/Memo

备注/Memo:
收稿日期:2022-11-22.
基金项目:中国地震局地震科技星火计划项目(XH202302); 震情跟踪定向工作任务(2021020102); 国家重点研发计划项目(2018YFC1504501-02).
第一作者简介:吴微微(1982-),正高级工程师,主要从事地震监测、数字地震学应用等方面研究.E-mail:673065247@qq.com.
通讯作者简介:苏金蓉(1971-),正高级工程师,主要从事地震监测预警、地震学应用研究.E-mail:sujr0816@163.com.
更新日期/Last Update: 2023-03-10