Advances in Seafloor Topography Inversion: Integrating Admittance Functions and Geophysical Parameter Optimization

Marine gravity anomalies arise from the interaction between seafloor topography and the isostatic adjustment of the lithosphere. The admittance function quantifies the ability to transform seafloor topography into gravity anomalies. By developing various admittance function models, the connection between lithospheric response-induced gravity anomalies and seafloor topography is established, facilitating the inversion of seafloor topography from marine gravity anomalies. Addressing the various geophysical parameters involved in the admittance function approach, this study used the CRUST1.0 model as a priori data and proposed the Moving Windows Admittance Technique, adopting a 40 km moving step and 600 km × 600 km window to invert an effective elastic thickness model at a resolution of 5′×5′. The “remove-restore” technique was also incorporated to enhance accuracy. In the Mariana Trench region, the study revealed that the trench-arc-basin system exhibits anomalously low lithospheric strength (effective elastic thickness around 2 km), whereas the subducting plate demonstrates greater strength. The constructed seafloor topography model was verified with shipborne bathymetric data, demonstrating accuracy comparable to the DTU18 model and outperforming the SIO V23.1 model (about 36.5% improvement). These findings highlight that optimizing geophysical parameters significantly enhances the accuracy of seafloor topography inversion, providing critical insights for future oceanic research.