| 宁夏中部小震震源机制解研究 |
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| 引用本文： | 田小慧,金春华,任家琪.宁夏中部小震震源机制解研究[J].防灾减灾学报,2016(3):7-14. |
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| 作者姓名： | 田小慧 金春华 任家琪 |
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| 作者单位： | 宁夏回族自治区地震局,宁夏 银川,750001 |
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| 基金项目： | 测震台网青年骨干培养专项(20140325) |
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| 摘 要： | 本文利用宁夏区域台网共27个台的宽频带数字地震记录,采用CAP方法和Snoke方法反演了宁夏中部19次ML3.0以上地震震源机制解。结果显示:东侧牛首山-罗山-固原断裂带和中部的烟洞山断裂带主要以右旋走滑为主,带少量逆冲分量,与实际主控断层的情况一致;西侧的中卫-同心断裂带以左旋走滑为主;19次地震的CAP法计算结果中的16次地震机制解走向在105~189o之间,另有2次为350o和353o,和断层走向基本一致。综合应力场研究结果表明该区域地震产生的震源区构造变形是近北东向发生压缩,近北西向发生相对扩张。对比2种方法计算结果发现,Snoke方法计算结果不理想。分析认为,一方面,宁夏台网台站间距较大,分布不理想;另一方面,识别小地震的初动及振幅比时存在误差。因此,对于西部台站稀疏地区CAP方法计算小震震源机制结果更为可靠。
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| 关 键 词： | 震源机制解 CAP法(Cutand Paste Method) Snoke法 |
STUDY ON THE FOCAL MECHANISM SOLUTIONS OF SMALL EARTHQUAKES IN THE MIDDLE AREAS OF NINGXIA |
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| Abstract: | In this paper ,used Digital seismic records with broadband of 27 stations in Ningxia area network, bying the CAP method and the Snoke method to inversion the focal mechanism solution 19 times above ML3.0 in the middle province. The result shows: Niushou mountain-Luo mountain-Guyuan fault zone in the east and Yandong mountain fault zone are dextral strike slip, with a small amount of thrust components, in line with the actual main control fault. Zhongwei-Tongxin fault zone in the west are sinistral strike slip. In 19 times CAP method computing results, 16 times focal mechanism solution trend were between 105o-189o, other 2 times were 350oand 353o, in line with the fault trend. The results of the field of stress indicate that The structure deformations in the focal region caused by earthquake are compression in NE and expansion in NW in II region. Compare two methods we found that calculation result of Snoke is poor. Analysis suggests, on the one hand, Ningxia network station spacing is bigger, the distribution is not ideal. On the other hand, errors are caused when initial motion and the amplitude ratio of small earthquakes are recognized. As a result, it is more reliable to use the CAP method to calculate the results of the focal mechanism for the small earthquakes in the sparse region of western station. |
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| Keywords: | focal mechanism solution Cut and Paste Method Snoke Method |
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