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Title:: Study on the Seismic Event Detection of Spectral Envelope Characteristics

Author(s):: ZHAN Xiaoyan; WANG Hengzhi; WANG Jun; MIAO Fajun; XUE Yingying; ZHU Shengchu; (Jiangsu Earthquake Agency,Nanjing 210014,Jiangsu,China)

Keywords:: aftershock sequence; first P arrival; seismic wave; spectral energy envelope; peak search

摘要:: 以声谱图像模式识别为基本思想,改进了基于地震波波谱包络分布特征的初至震相检测方法。改进后的算法,首先将波形记录特征转换为谱能量分布,以台站固有背景噪声的时频特征为基准,提取出记录信号的时频包络特征作为事件触发检测的目标函数。为降低主震尾波对检测后续余震的影响,采用非线性标度缩放因子对大于台站背景噪声水平的能量进行归一化处理。通过2组密集余震序列的实测结果表明:相对STA/LTA算法自动检测结果,新方法正确触发率提高约19.6%,漏触发率则降低了22.6%,表现出更强的抗干扰能力和触发效率,且运行速度快,能够满足地震实时处理系统的技术要求。

Abstract:: Based on the basic idea of acoustic spectrum pattern recognition,we have improved the first arrival seismic phase detection method based on the envelope characteristic of seismic wave spectrum. The improved algorithm is based on the time-frequency characteristics of the inherent ambient noise of station as the criterion of the event triggered detection,and the waveform record feature is converted to spectral energy distribution,and the scaling factor is used to normalize the energy that is larger than the ambient noise level of the station,in order to reduce the influence of the main shock wave on detecting subsequent aftershocks. Through the measurement of two sequences of dense aftershock,the results show that the method presented in this paper,the correct trigger rate is improved by about 19.6%,and the leakage trigger rate is reduced by 22.6%,compared with the automatic detection result of STA/LTA algorithm. It shows stronger anti-interference ability and trigger efficiency,and it is similar to the STA/LTA algorithm,which is running fast and can meet the requirements of the real-time seismic processing system.