Focal depths for moderate-sized aftershocks of the Wenchuan MS8.0 earthquake and their implications
Focal depths for moderate-sized aftershocks of the Wenchuan MS8.0 earthquake and their implications
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DOI：
10.1007/s11430-008-0140-2
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发表时间：
2008-11
期刊：
影响因子：
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通讯作者：
Ruiqing Zhang;Qingju Wu;Yonghua Li;Z. Ding;Rong-sheng Zeng
中科院分区：
文献类型：
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作者：
Ruiqing Zhang;Qingju Wu;Yonghua Li;Z. Ding;Rong-sheng Zeng
首次采用滑动窗互相关方法，通过测量sPn和Pn震相的时间间隔，从区域地震记录中识别sPn震相，并约束震源深度。利用陕西、青海、甘肃、云南和四川区域地震宽带台网记录的资料，给出了汶川8.0级地震17个中等余震（MS ≥ 5.0）的震源深度。结果表明，余震的震源深度范围为8 ~ 20 km，并在32.5°N处有两个平均深度聚成一组，南11 km，北17 km，表明这些余震是中上地壳的震源。结合其他研究结果，我们认为龙门山断裂不是一条贯通的地壳断裂，平武-青川断裂可能不是龙门山逆冲断裂向北延伸的产物。
Sliding-window cross-correlation method is firstly adopted to identify sPn phase, and to constrain focal depth from regional seismograms, by measuring the time separation between sPn and Pn phases. We present the focal depths of the 17 moderate-sized aftershocks (MS⩾5.0) of the WenchuanMS8.0 earthquake, using the data recorded by the regional seismic broadband networks of Shaanxi, Qinghai, Gansu, Yunnan and Sichuan. Our results show focal depths of aftershocks range from 8 to 20 km, and tend to cluster at two average depths, separate at 32.5°N, i.e., 11 km to the south and 17 km to the north, indicating that these aftershocks are origin of upper-to-middle crust. Combined with other results, we suggest that the Longmenshan fault is not a through-going crustal fault and the Pingwu-Qingchuan fault may be not the northward extension of the Longmenshan thrust fault.