汶川地震前后各台站台基地动噪声变化分析

Analysis of the Changes of Station Background Noise before and after Wenchuan Earthquake

利用"5·12"汶川地震前后三分向连续波形数据,对四川台网51个测震台站台基噪声功率谱进行计算,得到每个台站速度功率谱密度曲线及地面运动的速度记录的功率谱密度在1~20 Hz频带范围的均方根值,对地震前后各台地噪声水平进行了对比分析,结果表明:(1)51个台站的速度功率谱密度曲线均在高噪声和低噪声模型曲线间;(2)历经"5·12"汶川地震及"4·20"芦山地震后所有子台均适应宽频带观测要求,台站观测环境噪声水平全部符合规范要求。

We use the continuous waveform data of 51 observation stations of the Sichuan Network before and after the Wenchuan Earthquake to calculate the base noise power. And then we plot the velocity power spectral density curve for each seismic stations and ground motion velocity records spectral density curve in 1-20 Hz frequency range of the root mean square value. Our results show that：（ 1） the power spectral density curves of 51 stations are between the curve of high noise and low noise model of the earth.（ 2） After the Wenchuan Earthquake and the Lushan Earthquake 51 seismic stations are suitable for broadband observation and all environmental requirements are satisfied according to the specification.