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地震 ›› 2006, Vol. 26 ›› Issue (1): 1-9.

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2003年云南大姚6.2级和6.1级地震余震S波分裂研究

邬成栋1, 付虹1, 刘杰2   

  1. 1.云南省地震局, 云南 昆明 650224;
    2.中国地震台网中心, 北京 100036
  • 收稿日期:2005-05-30 修回日期:2005-07-29 发布日期:2021-11-01
  • 作者简介:邬成栋(1979-), 男, 甘肃张掖人, 硕士, 主要从事地震学、 地震预报等研究。
  • 基金资助:
    “十五”国家科技部重点攻关项目(2004BA601B01-04-03); 中国地震局地震活动图像与数字地震应用实验室联合资助

Shear wave splitting of aftershocks with M=6.2 and 6.1 after Dayao Earthquake in Yunnan 2003

WU Cheng-dong1, FU Hong1, Liu Jie2   

  1. 1. Earthquake Administration of Yunnan Province, Kunming 650224;
    2. China Earthquake Networks Center, CEA, Beijing 100036, China
  • Received:2005-05-30 Revised:2005-07-29 Published:2021-11-01

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摘要： 利用2003年云南大姚6.2、 6.1级两次地震的余震资料对该区进行了S波分裂研究。 结果表明, 云南大姚地区的快剪切波偏振的优势方向约为N33°W, 与该区域的区域主压应力的方向一致。 通过对比6.2级余震和6.1级余震的偏振方向和延迟时间, 可以看到6.1级地震后明显的应力释放现象, 在几次强余震前, 均观测到延迟时间呈现增加的特征, 并且几次地震在即将发生之前的短时间内还观测到延迟时间有减小的现象, 这一现象符合震前应力长时间积累和短时间应力释放的结论, 时间延迟在强震前会出现下降具有重要的地震短临预测意义。 研究认为S波分裂参数可以反映区域应力场的动态变化信息, 为应力场研究与地震预测提供有用的信息。

关键词: S波分裂, 大姚地震序列, 延迟时间

Abstract: A study of shear wave splitting is made through the recordings of 6.2 and 6.1 aftershocks in Yunnan 2003. The results show that the preponderant polarizations of fast shear wave is N33°W in Dayao, it accords with the regional predominant direction of principal compressional stress. Through contrasting polarizations and time delay of two aftershocks, we can see evident stress relaxation after 6.1 earthquake. Before strong aftershocks, we observed that the time delay basically would increase. However the time delay abruptly decreased immediately before several strong aftershocks. It accords with the conclusion that long-term stress accumulation and short-term stress relaxation is existed before earthquakes. It is significant for the short-term earthquake prediction that the time delay will decrease before strong earthquakes. The result suggests the parameters of shear wave splitting may reflect the dynamic change of region stress field and provide useful information for the study of stress field and earthquake prediction.

Key words: Shear wave splitting, Sequence of Dayao earthquake, Time delay

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