| 利用初至P震相测定石嘴山ML4.4地震序列的震源深度 |
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| 引用本文： | 曾宪伟,莘海亮,马翀之,许晓庆.利用初至P震相测定石嘴山ML4.4地震序列的震源深度[J].地震学报,2017,39(1):13-22. |
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| 作者姓名： | 曾宪伟 莘海亮 马翀之 许晓庆 |
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| 作者单位： | 1).中国银川 750001 宁夏回族自治区地震局 |
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| 基金项目： | 宁夏回族自治区重点研发计划(2016KJHM135)和宁夏自然科学基金项目(NZ14228)联合资助.宁夏回族自治区重点研发计划2016KJHM135和宁夏自然科学基金项目NZ14228 |
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| 摘 要： | 基于初至P震相较易辨识、读取误差小、有效震相丰富等优点，提出联合Pg与Pn震相到时数据测定震源深度的方法，并将其应用于石嘴山ML4.4地震序列(11次)的震源深度计算，结果显示该地震序列的震源较浅，这也是此次有感地震震感强烈的原因之一．然后利用初至P震相到时方法分别计算了双层和4层地壳速度模型下的震源深度，并与双差定位所得深度进行对比，结果显示: 利用初至P震相到时方法较双差定位方法得到的震源深度整体上一致性较好，但前者得到的震源深度较之后者略深；对于双层与4层地壳速度模型，二者的震源深度计算结果具有较好的一致性．因此，基于可靠区域地壳速度模型下的初至P震相到时方法可以应用于震源深度的计算，并能够取得较好的结果．另外，石嘴山ML4.4地震序列的主震深度为7—8 km，最大余震深度为6 km，根据银川盆地的速度成像结果可知，主震和最大余震发生于银川盆地基底下部；其余地震的震级偏小，多集中于3—5 km深度，主要发生于银川盆地基底顶部或基底覆盖层内．
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| 关 键 词： | 初至P震相 震源深度 银川盆地 速度模型 |
| 收稿时间： | 2016-05-08 |
Calculation of focal depths of Shizuishan ML4.4 earthquake sequence by using the first arrival P phases |
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| Affiliation: | 1).Earthquake Administration of Ningxia Hui Autonomous Region, Yinchuan 750001, China2).Geophysical Exploration Center, China Earthquake Administration, Zhengzhou 450002, China3).School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China |
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| Abstract: | In this paper，the focal depths of eleven events of the Shizuishan ML4.4 earthquake sequence were calculated by using the data of first arrival P phases. The results show that the earthquake sequence was composed of shallow earthquakes，which is one reason for the earthquakes felt strongly. Then the focal depth of the sequence was calculated based on double-layer and four-layer velocity models by the method of first arrival P phase. And the above results were compared with the double difference location. Firstly，the comparison of the focal depth obtained by the double difference location method with that by the first arrival P phase method show that the two results are consistent with each other on the whole，but the depth got by the latter method is rela-tively deep. Secondly，the results based on double-layer and four-layer crustal velocity models are in good agreement. The depth of the main shock is 7--8 km，and the depth of the largest aftershock is 6 km. According to the velocity imaging results of Yinchuan basin，it is deduced that the main shock and the largest aftershock occurred in the lower part of the Yinchuan basin basement. In addition，the other aftershocks are small with depth concentrating in 3--5 km，and they occurred mainly on the top of the basement of Yinchuan basin or within overburden layer. |
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