Model and prediction relationship of sound velocity and porosity of seafloor sediments

Abstract

The relationship between sound velocity and porosity in seafloor sediments is widely utilized for predicting or inverting sediment acoustical and physical parameters. This paper analyzes the theoretical relationship between sound velocity and porosity using the General Model of Sound Speed (GMSS). The GMSS model elucidates an empirical equation relationship in the form of a quadratic fitted polynomial based on actual measurement data from the South China Sea. The accuracy of the GMSS model and the regression empirical equation are found to be consistent, as demonstrated by the relative error, absolute error, and standard deviation of the sound velocity predictions. Our findings suggest that if the scattering of measured data is inherent to seafloor sediment, the empirical equation fails to adequately explain sediment variations and lacks broad applicability for accurate prediction and calculation. Additionally, we observe that a ± 5% relative error in porosity has minimal impact on the application of the GMSS model and empirical equations for predicting sound velocity errors. However, the empirical equation, relying solely on the porosity parameter, inadequately accounts for sound velocity scattering in seafloor sediments with the same porosity due to inherent limitations. In contrast, the GMSS model can incorporate additional physical parameters beyond porosity to better explain and predict sound velocity in seafloor sediments scattering in seafloor sediments with the same porosity, albeit with increased complexity. This paper provides an analytical method and theoretical foundation for inverting or predicting the relationship between sound velocity and porosity of seafloor sediments.