Inversion of the sediment sound velocity in the Northern South China Sea

Acoustic models are effective methods for inverting the geo-acoustic properties of seafloor sediments. To investigate the main sediment types in the northern South China Sea, 221 sediment core samples containing three sediment types (clayey silt, silty clay, muddy sand) were collected, and the geo-acoustic properties of the sediments were measured and analyzed. The results show that the same sediment type, shows different acoustic properties for different sedimentary environments. To verify the applications of different acoustic models, three acoustic models (the BS, EDFM and VGS model) were used to invert the sound velocities. It was observed that when porosity is less than about 0.75, the predicted velocity values from the three models are close to the measured values. As the porosity increases, the variation trend of VGS model is more in line with the measured data, while the BS and EDFM model has a relatively large error with the measured data.It seems that the VGS model, which incorporates the properties of both fluids and elastic solids, has a relatively broader scope of application. while the BS and EDFM models are susceptible to the porosity and particle size of the sediment.