Application of broadcast RTK for automated static correction in 3D sub-bottom profiling

Abstract

Various types of 3D sub-bottom profilers (SBPs) have been developed to widen the swath coverage of conventional single-channel SBPs. Nevertheless, the data acquisition process is frequently influenced by fluctuations in water depth, attributed to swells and tidal variations. These fluctuations, particularly pronounced during 3D sub-bottom profiling when source frequency bands reach several kHz, significantly distort the two-way travel time of seismic reflections, potentially hindering the generation of high-fidelity seismic cubes. In this study, high-precision 3D coordinates of each source and receiver channel were recorded in real-time during data acquisition and employed for pre-stack Kirchhoff depth migration to produce a static corrected seismic cube. To streamline the acquisition of positioning data for the survey system operating in coastal areas, broadcast real-time kinematics (RTK) was integrated to receive RTK correction signals via broadcast radio waves, facilitating a real-time method for generating 3D coordinates for each source and receiver channel. Additionally, a Kirchhoff migration algorithm was devised to efficiently generate the static corrected seismic cube using the 3D coordinates of the source and receiver. Field data were collected in waters near Jindo, South Korea, where tidal differences reached 4 m, resulting in the production of an ultrahigh-frequency seismic cube with a 50 cm bin size. The robustness and applicability of the automated static correction method were validated through analysis of the seismic cube.