陶乐地震台地表与井下地震计记录波形对比研究

为定量研究地表与井下背景噪声的异同，在同一台站地表架设地震计，与井下地震计进行同步观测。首先选取样本数据计算背景噪声功率谱密度，分析不同类型地震计安装在不同深度时功率谱密度及平均噪声RMS值的变化特征。通过对比分析3种地震计记录的近震和远震波形发现，地表宽频带、短周期和井下短周期地震计记录的近震波形都比较清晰，震相易于识别，且地表宽频带与井下短周期地震计记录的远震波形更清晰；而地表短周期地震记录的远震波形较差，失真严重，震相不易识别。在进行震源频谱对比分析中发现，相对于地表地震计，井下地震计记录的近震波形在7~12 Hz频段受干扰较为严重，远震波形则在4~7 Hz频段受干扰严重，震相分析时需慎重处理。

Comparative Study of Waveform Recorded by the Ground and Borehole Seismograph in Taole Seismic Station

To quantitatively study the similarities and differences between ground and borehole background noise, we set up a seismograph on the ground of the Taole Seismic Station and use borehole seismograph for simultaneous observation. Firstly, sample data are selected to calculate the power spectral density of background noise. We analyze the power spectral density and average noise RMS values of different seismograph at different depths. The near and far earthquakes recorded by three seismographs are compared and analyzed. The results show that the near seismic waveform recorded by surface broadband, short period and underground short period seismograph are relatively clear and easy to identify seismic phases. Moreover, the teleseism waveform recorded by surface broadband and underground short period seismograph is relatively clear, while the teleseism waveform recorded by surface short period seismograph is poor, the waveform distortion is serious, and identifying the seismic phase is difficult. At the same time, in analysis and comparison of the recorded seismic source spectrum, we find that the near earthquakes recorded by the borehole seismograph are seriously disturbed in the frequency band of 7 to 12 Hz compared with the surface seismograph. The recorded teleseisms are seriously disturbed in the frequency band of 4 to 7 Hz, so they need to be handled carefully in seismic phase analysis.