An Improved Iterative Gravity Inversion Method for Moho topography and Its Application to the South China Sea

Summary Before inverting the Moho topography, the Parker-Oldenburg method requires the determination of appropriate inversion parameters, exponential term and low-pass filtering, in order to minimise the artificial smoothing introduced by these factors, which would suppress the genuine short-wavelength undulations of Moho topography. Previous research has tended to focus on addressing the individual impact of a single factor, whilst neglecting other factors. To address this, we proposed the PO-PSO method. This method builds upon the Parker-Oldenburg method, employing a particle swarm optimisation to determine the correction terms of Moho topography, thereby restoring the high-frequency features within the Moho topography. Synthetic tests show that, compared with the Parker-Oldenburg method, the Moho topography obtained by PO-PSO is closer to the synthetic model under both noise-free and noisy conditions, with an improvement in accuracy of 30∼32%. In practice, we utilised PO-PSO to invert the Moho topography of South China Sea. The results reveal that the Moho topography in the study area ranges from 4.59 to 27.85 km. When compared against multiple seismic profiles, the root mean square error of final model was 1.57 km. This represents an 11.8% improvement in accuracy compared to the initial model.