Noise Reduction from Vertical-Component Seismograms Recorded by Broadband Ocean-Bottom Seismometers Deployed at the Western Pacific
Noise Reduction from Vertical-Component Seismograms Recorded by Broadband Ocean-Bottom Seismometers Deployed at the Western Pacific
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DOI：
10.1785/0120220256
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发表时间：
2023-04
影响因子：
3
通讯作者：
Y. Kawano;T. Isse;H. Kawakatsu;H. Shiobara;N. Takeuchi;H. Sugioka;Younghee Kim;H. Utada;Sang‐Mook Lee
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文献类型：
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作者：
Y. Kawano;T. Isse;H. Kawakatsu;H. Shiobara;N. Takeuchi;H. Sugioka;Younghee Kim;H. Utada;Sang‐Mook Lee
本文对部署在西太平洋海底的日本宽带海底地震仪（bobss）作为oldest1阵列观测记录的数据进行了改进，改进了现有的降噪方法。我们消除了在低频地震图中占主导地位的倾斜和顺应噪声。我们估计了水平分量到垂直分量的地震记录的噪声传递函数，以消除垂直分量中的倾斜噪声。在大约一年的观测期内，倾斜噪声传递函数是时不变的，并且在低频（<0.06 Hz）时是同相的，这与之前的研究不同，使我们能够应用恒定的传递函数并估计传感器的倾斜。我们估计了从压力分量到垂直分量记录的噪声传递函数，并去除了0.002-0.02 Hz频率范围内的顺应性噪声。由于消除了倾斜和顺应性噪声，在低于0.03 Hz的频率下，噪声水平降低了20 dB。我们表明，使用恒定传递函数的倾斜降噪适用于配备CMG-3T传感器的日本bbbs。估计Oldest-1阵列的倾角为0.3°-1.1°，最大倾斜方向沿着传感器的H1分量，这归因于CMG-3T传感器的结构。
We modified existing methods of noise reduction to data recorded by Japanese broadband ocean-bottom seismometers (BBOBSs) deployed on the western Pacific seafloor conducted as the Oldest-1 Array observation. We removed the tilt and compliance noise that are dominant in low-frequency seismograms. We estimated the noise transfer function from the horizontal- to vertical-component seismograms to remove tilt noise from the vertical component. Throughout the observation period of about one year, the tilt noise transfer function was time-invariant and in phase at low frequencies (<0.06 Hz), which, in contrast to previous studies, enabled us to apply a constant transfer function and to estimate the tilt of the sensor. We estimated the noise transfer function from the pressure- to the vertical-component records and removed the compliance noise in the frequency range of 0.002–0.02 Hz. As a result of tilt and compliance noise removal, noise levels were reduced by up to 20 dB at frequencies below 0.03 Hz. We show that tilt noise reduction using the constant transfer function is appropriate for Japanese BBOBSs equipped with the CMG-3T sensor. Tilt angles of Oldest-1 Array are estimated as 0.3°–1.1° and maximum tilt directions are along the H1 component of the sensor, which are attributed to the architecture of the CMG-3T sensor.