Polarization Analysis Method for Seismic Phase Identification in Three-Component Seismic Data from Seismic Stations

地震震相识别是地震定位与地球内部结构研究的基础。传统方法在复杂构造区易受波场混叠和噪声干扰，而极化分析通过提取地震波质点运动的矢量特征，为震相识别提供了物理意义明确的判据。文章基于三分量地震信号的极化特性，利用协方差矩阵特征值分解方法计算极化参数(线性极化率、平面极化率、方位角与入射角)，揭示了P波、S波、面波等震相的极化差异：P波呈线性极化，方位角与震源方位一致；S波极化方向垂直于传播方向；瑞雷面波及勒夫面波表现为平面内极化。以西藏定日县6.8级地震为例，极化分析成功识别纵波初至(方位角约103度)、横波及面波，参数时序变化与理论模型吻合。研究表明，极化分析方法能够有效区分不同震相。Seismic phase identification is fundamental for earthquake localization and studies of Earth’s internal structure. Traditional methods are prone to wavefield aliasing and noise interference in complex tectonic regions, while polarization analysis provides physically interpretable criteria for phase identification by extracting vector features of seismic wave particle motion. This study leverages the polarization characteristics of three-component seismic signals and employs covariance matrix eigenvalue decomposition to calculate polarization parameters (e.g., linear polarization ratio, planar polarization ratio, azimuth angle, and incidence angle), revealing distinct polarization differences among phases such as P-waves, S-waves, and surface waves. Specifically, P-waves exhibit linear polarization with azimuth angles consistent with the source direction; S-waves are polarized perpendicular to the propagation direction; Rayleigh waves and Love waves exhibit in-plane polarization. Using the magnitude 6.8 earthquake in Tingri County, Tibet, as an example, polarization analysis successfully identified the P-wave onset (azimuth angle ~103˚), S-waves, and surface waves, where the temporal variations of these parameters align with theoretical models. The results demonstrate that polarization analysis effectively distinguishes different seismic phases.