辽宁岫岩地震序列地震运动学参数时变特征的研究

Study on the time-varying seismic kinematic parameters of Xiuyan earthquake sequence in Liaoning Province

利用辽宁数字地震台网1999年8月至2000年12月的数字地震资料, 详细研究了岫岩地震序列(1999年11月至2000年1月)前后直达S波的最大加速度峰值的时间变化特征, 及其与构造环境背景应力和视应力变化的一致性, 得到了地震运动学参数在前主余震形成和发生的演化过程中明显的差异性变化。为探索前震的判别和强余震的预测, 提供了可快速精确测定的物理参数和掌握地震构造应力背景变化的物理信息。通过对单台视应力、剪应力τ0 值、S波加速度峰值时间变化过程的对比分析表明, 这3 个参量都是强烈地依赖于应力背景强弱的的物理量, 因此反映的是一种的物理过程, 具有一致的物理意义, 其时间变化过程具有很好的一致性。这3种方法由于其计算过程简便, 在地震分布变化很小, 台站位置相对固定的条件下可较为精确的测定, 其异常的幅度明显高于正常背景值, 因此有较为显著的异常分辨率。使用者可根据具体观测条件和现场研究的需要, 选取合适的研究方法。

Based on studying the consistency of time-varying direct S wave maximum acceleration peak value and the change in tectonic environmental background stress and apparent stress before and after Xiuyan earthquake sequence (from November 1999 to January 2000) in detail using the digital seismic data from August 1999 to December 2000 recorded by Liaoning digital seismic network, we obtained the result that the seismic kinematic parameters changed differently in the evolution process of the pre-main-after shock generation and occurrence. The physical parameters can be determined rapidly and accurately, which provided physical information of change in seismic tectonic stress for identifying pre-earthquakes and predicting strong aftershocks. The contrastive analysis of time-varying process for apparent stress, shear stress value τ__0 and S wave acceleration peak value at single station shows that those three physical parameters strongly depend on the stress background and they reflect the same physical process, have coincident physical meaning and their time-varying processes accord well with each other. As the methods of calculating these three parameters are simple, they can be accurately determined in the conditions that the variation for earthquakes distribution is small and the position of station is relatively fixed. Their abnormal values are much higher than the normal background values, so they has high abnormal resolution. Users can choose appropriate research method according to the observation condition and necessity for field study.