Ambient noise interferometry using ocean bottom seismometer data from active source experiments conducted in the southernmost Mariana Trench

Abstract

Ocean bottom seismometers (OBSs) have been used to detect submarine structural and tectonic information for decades. According to signal source controllability, OBS data have generally been classified into active and passive source data categories. The former mainly focuses on the compressional wave (P-wave) velocity inversion and always lacks valid information about the shear wave (S-wave) velocity structure. While the latter provides structural information with limited resolution due to the aperture of the stations. Overcoming the barriers between processing these two data types will allow the reuse of a vast amount of data from active source experiments to explore the submarine S-wave velocity structural properties. Here, we creatively applied ambient noise interferometry to invert the S-wave velocity structure using data from active source OBS deployment conducted in the southernmost Mariana subduction zone, which had already been utilized to detect submarine P-wave velocity structure. Considering the short time duration and relatively low quality of this type of data, a combined method of short-segment cross-correlation and selected time-frequency domain phase-weighted stacking was adopted to obtain stable cross-correlation functions, which were subsequently used to invert S-wave velocity structures. Compared to previous studies using different methods, our result sheds new light on the crust and upper mantle structure of the southernmost Mariana subduction zone. This method could be used to detect more information based on the reutilization of existing active source OBS data.