2020年河北唐山M5.1地震震前地脉动异常特征初探

对2020年唐山M5.1地震前河北数字测震台承德、涞源、滦县、京唐港和迁西台站的数据资料进行分析，通过小波分解、功率谱分析、快速傅里叶变换等方法处理数据研究震前地脉动的异常变化特征。结果显示:① 唐山地震前，5个台均出现低频地脉动前兆异常，且4个台站低频异常具有一致性；② 4个台震前表现为振幅趋势上升，震后逐步下降；③ 4个台震前PSD变化具有一致性，震前趋势上升震后逐渐下降，且与振幅曲线呈相同趋势。 

Preliminary study on abnormal characteristics of microtremor before Hebei Tangshan M5.1 earthquake in 2020

This paper analyzes the data of Hebei digital seismographic stations Chengde, Laiyuan, Luanxian, Jingtanggang and Qianxi before the Tangshan M5.1 earthquake in 2020. The data are processed by wavelet transform, power spectrum analysis, fast Fourier transform and so on to study the abnormal variation characteristics of the microtremor before earthquake. The results show that: ① Before the Tangshan earthquake, there are low-frequency microtremor precursory anomalies at 5 stations, and the anomalies of low-frequency at 4 stations are consistent. ② The amplitudes of the four stations increased before the earthquake and decreased gradually after the earthquake. ③ The PSD varieties of the four stations before earthquake are consistent. They all increased before the earthquake and gradually decreased after the earthquake, and the trend is the same as the amplitude curve.