Predicting Bathymetry in Mariana Trench Using Gravity-geologic Method

Based on the gravity geology method (GGM), this study inverted the submarine topography of the Mariana Trench (in the range of 142°36'—147°18' E, 23°—27° N) by using 6 736 known-depth points (controlling points) and satellite altimetry gravity anomalies and density contrast of 1.2 g/cm. The standard deviation between the inverted topography and known-depth points (checking points) is 152.9 m, with an average error of (±3.0) m, mean square deviation of 153.0 m, which are better than ETOPO1 model and the gridded model which was directly interpolated from controlling points. This study then analyzed the power spectral densities of GGM model, ETOPO1 model and gridded model, and the results showed that these three models have the same energy in long and middle wave topography, but in short wave topography, the energy of GGM model was higher than the other two models, indicating that GGM method could better describe the detailed seabed topography and landform. Finally, two checking lines were selected to compare with the GGM model, and the results showed that the GGM method had a better inversion effect in the area with small topography relief than in those with large topography relief.