Preprocessing of passive-source ocean-bottom seismometer data in the Mariana subduction zone

The data collected by ocean-bottom seismometers are unique compared to that of land seismic stations and require preprocessing before use. In this study, we focus on preprocessing seismic data obtained from a passive-source experiment in the Mariana subduction zone conducted by the Institute of Deep-Sea Science and Engineering, Chinese Academy of Sciences from 2018 to 2019. We outline the steps involved in preprocessing the data, including time correction using the ocean background noise cross-correlation function, tilt correction using a transfer function and orientation correction based on seismic wave polarization. Our results show that the maximum clock drifting was similar to 4 s on two stations (K06 and K20), whereas the rest of the station waveforms have clock drifting of less than 2 s. Among stations, only the K06 station is tilted, and the tilt angle is 19.82 degrees. We use the P-wave and Rayleigh wave polarization methods to determine the orientation. Our results indicate that the error in the result obtained using the P-wave polarization method is less than that of the Rayleigh wave polarization method. Additionally, we address the advantages and disadvantages of these preprocessing techniques. Our goal is to offer a comprehensive overview of the preprocessing process, to assist beginners in the field and to serve as a foundation for future research in passive-source ocean-bottom seismometers.