2021年江苏盐城海域MS5.3地震震源机制中心解及基于震源机制的区域应力场反演
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黄少华(1998—),男,硕士研究生。主要从事震源机制、应力场反演等方面的研究。E-mail:1961921173@qq.com

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P315.1

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中央高校科研业务费专项(ZY20215117);国家自然科学基金(42174074,41674055)资助


Central Focal Mechanism of 2021 MS5.3 Yancheng Offshore Earthquake and Regional Stress Field Based on Multiple Earthquakes’Focal Mechanisms
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    摘要:

    2021 年 11 月 17 日江苏盐城近海区域发生 MS5.3 地震,该地震的发震机制及其原因引起地球科学家的广泛关注,为分析地震发生的原因,本次地震的震源机制解和区域应力场的精确确定是必要的。本研究综合多种机构的震源机制解数据确定了可信的震源机制中心解。为保证震源区域应力场求解的精度,本文搜集了地震周围 2016 年以前的历史震源机制解数据,并利用地震观测报告,得到 22 个 2016 年之后地震的震源机制解,使用结合后的震源机制解数据求解了江苏盐城海域 MS5.3 地震周围的应力场。最终结果为:江苏盐城海域 MS5.3 地震的震源机制中心解节面 I 走向 104.95°,倾角 70.91°,滑动角 26.45°,节面 II 走向 5.70°,倾角 65.11°,滑动角 158.86°;研究区域的主压应力呈 ENE‐WSW 向分布,主张应力呈 NWN‐SES 向分布。将应力场投影到震源机制中心解节面上,发现两个节面均处于相对剪应力很高的水平,说明此次地震是在构造应力场作用下发生在剪应力最大释放节面上的地震,是应力积累后的一次正常释放,周边再次发生大地震的可能性减小。考虑到应力场投影到节面 II 的相对剪切应力较节面 I大,并且节面 II与苏北—滨海断裂走向更为接近,确定节面 II为本次地震的发震断层面。

    Abstract:

    On November 17,2021, an MS5.3 earthquake occurred in the offshore area of Yancheng, Jiangsu Province, China. The seismogenic mechanism and its causes have attracted extensive attention of earth scientists. To analyze the causes of the earthquake, it is necessary to accurately determine the focal mechanism solution of the earthquake and the regional stress field. In this study, a credible central focal mechanism solution was determined by synthesizing the focal mechanisms of various institutions. To ensure the accuracy of solving the stress field in the source region, this study collects the historical source mechanism solution data around the earthquake before 2016, and uses the earthquake observation report to obtain 22 source mechanism solutions after 2016. The combined source mechanism solution data is used to solve the stress field around the MS5.3 earthquake in Yancheng Sea, Jiangsu Province. The final results are as follows: the central focal mechanism of MS5.3 earthquake in Yancheng Sea area of Jiangsu Province plane I strike angle is 104.95°, dip angle is 70.91°, slip angle is 26.45°, plane II strike angle is 5.70°, dip angle is 65.11°, slip angle is 158.86°; The predominant direction of main compressive stress in this area is ENE-WSW, and the dominant direction of stress is NWN-SES. Projecting the stress field onto the central focal mechanism's planes, both of planes are at a high level of relative shear stress, indicating that the earthquake occurred at the maximum shear stress release plane under the action of the tectonic stress field. It is a normal release after stress accumulation, and the possibility of a large earthquake occurring around is reduced. Considering that the relative shear stress projected by the stress field to Ilane II is larger than that of Plane I, and Plane II is closer to the strike of the Subei-Binhai fault, it is determined that the plane II is the seismogenic fault plane of this earthquake.

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黄少华,万永革,孙业君,许鑫,余海琳,冯淦,李枭.2021年江苏盐城海域MS5.3地震震源机制中心解及基于震源机制的区域应力场反演[J].防灾减灾工程学报,2023,43(6):1266-1274

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  • 收稿日期:2022-09-22
  • 最后修改日期:2022-11-19
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  • 在线发布日期:2024-01-11
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