| 基于精定位余震序列的2019年四川长宁MS6.0地震等震线研究 |
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| 引用本文： | 徐志双,刘杰,郑通彦,任静,陈雅慧,李晓丽.基于精定位余震序列的2019年四川长宁MS6.0地震等震线研究[J].地震学报,2020,42(4):447-456. |
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| 作者姓名： | 徐志双 刘杰 郑通彦 任静 陈雅慧 李晓丽 |
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| 作者单位： | 中国北京 100045 中国地震台网中心 |
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| 基金项目： | 地震科技星火计划（XH20071Y）、中国地震局地震应急青年重点任务（CEA_EDEM_202024）和中国地震台网中心青年科技基金（QNJJ201909）共同资助 |
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| 摘 要： | 采用双差定位法对四川长宁MS6.0主震和24小时内的余震进行重新定位，对重定位的余震进行震级加权的方向分布拟合得到余震区的长轴和中心点，并与Ⅶ度烈度等震线长轴和等震线几何中心进行比较，结果显示:余震区长轴方向与Ⅶ度区长轴方向相近（差值为4°），且长度近似相等（差值为4 km）；余震中心与等震线中心均位于重定位主震的西北方向，且等震线中心相对余震中心向上盘方向偏移约3.0 km。长宁MS6.0地震等震线图呈现出明显的上/下盘效应，上盘高烈度区面积约为下盘的2.1倍，等震线中心也向上盘方向偏移。两小时和24小时的余震方向分布拟合具有很好的一致性，拟合结果与等震线具有相同规律。研究成果可为浅源中强震预评估烈度图的修正提供一种思路。
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| 关 键 词： | 余震 等震线 双差定位 震源机制 方向分布 |
| 收稿时间： | 2020-04-21 |
Isoseismal line of Sichuan Changning MS6.0 earthquake in 2019 based on precisely located aftershocks sequence |
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| Affiliation: | China Earthquake Networks Center，Beijing 100045，China |
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| Abstract: | The double-difference location method was utilized to determine the locations of the main shock of Changning MS6.0 earthquake in Sichuan Province and its aftershocks within 24 hours. A magnitude-weighted direction distribution fitting for the relocated aftershocks results in the major axis and the center of aftershock area. A comparison with the major axis and geometric center of the isoseismal line of intensity Ⅶ shows that the directions of major axis between the aftershock area and the Ⅶ intensity area are close to each other （with a difference of 4°）, and the length of the two axes are approximately equal （with a difference of 4 km）. Furthermore, the centers of the aftershock area and isoseismal line both locate northwest of the relocated main shock, and the isoseismal center deviates towards the hanging wall from the center of the aftershock area with a distance of about 3.0 km. The isoseismal map of Changning MS6.0 earthquake shows visible hanging wall/footwall effects, i.e., the high-intensity area of the hanging wall is almost 2.1 times larger than that of the footwall, and the isoseismal center shifts towards the hanging wall. The fitting result of the aftershocks within 2 hours is consistent with that of 24 hours, and the comparison with isoseismal map results in the same conclusion. The results of this research might provide a new idea for the revision of the pre-assessment intensity map for shallow-source moderate-strong earthquakes. |
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