Frequency Limit for the Pressure Compliance Correction of Ocean-Bottom Seismic Data
Frequency Limit for the Pressure Compliance Correction of Ocean-Bottom Seismic Data
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DOI：
10.1785/0220190259
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发表时间：
2019-12
影响因子：
3.3
通讯作者：
C. An;S. S. Wei-S.;C. Cai;H. Yue
中科院分区：
文献类型：
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作者：
C. An;S. S. Wei-S.;C. Cai;H. Yue
海底地震仪（OBS）的垂直记录通常在低频下有噪声，其中一个重要的噪声源是海洋表面水波引起的海底压力变化。海底压力和垂直海底运动之间的关系，称为顺应压力传递函数（PTF），可以使用背景地震数据得出。地震时，地震信号也会产生海底压力波动，海底压力与海底垂直运动之间的关系在本文中称为地震PTF。传统上，我们使用全压力记录和顺应性PTF来消除顺应性噪声；忽略地震引起的压力和地震PTF，这可能会扭曲原始信号。在本文中，我们分析了 24 个 OBS 的数据，水深范围为 107 至 4462 m。我们发现，对于大多数站来说，所研究的频率范围（0.01-0.2 Hz）可以根据水深分为四个频段。在最低频率频段（I）（水深1109和2650m分别为0.11和>0.08Hz），顺应性噪声可以忽略不计，海底压力主要是由海底运动引起的。因此，在频带 (I) 中可以安全地忽略顺从性。
Vertical records of ocean-bottom seismographs (OBSs) are usually noisy at low frequencies, and one important noise source is the varying ocean-bottom pressure that results from ocean-surface water waves. The relation between the ocean-bottom pressure and the vertical seafloor motion, called the compliance pressure transfer function (PTF), can be derived using background seismic data. During an earthquake, earthquake signals also generate ocean-bottom pressure fluctuations, and the relation between the ocean-bottom pressure and the vertical seafloor motion is named the seismic PTF in this article. Conventionally, we use the whole pressure records and the compliance PTF to remove the compliance noise; the earthquake-induced pressure and the seismic PTF are ignored, which may distort the original signals. In this article, we analyze the data from 24 OBSs with water depth ranging from 107 to 4462 m. We find that for most stations, the investigated frequency range (0.01–0.2 Hz) can be divided into four bands depending on the water depth. In band (I) of lowest frequencies (0.11 and >0.08 Hz for water depth of 1109 and 2650 m, respectively), the compliance noise is negligible, and the ocean-bottom pressure is mostly caused by the seafloor motion. Thus, the compliance can be safely ignored in frequency band (I).