Gravity anomaly and satellite altimetry in the China Seas: Applications to geodynamics

Satellite altimetry has become an operational remote sensing technique with important applications to geodynamics. In the present paper, ocean floor topography and tectonic detection in the deep earth are investigated using gravity anomalies from global gravity models and satellite altimetry corrected for waveform distortions. We compute the spherical harmonic degree components of the gravity anomaly from gravity models (up to degree 360), and use inverse the Vening Meinesz formula in the remove-restore procedure to obtain the residual gravity anomaly components higher than degree 360. This paper is intended to give a geodynamical analysis on the gravity anomaly components from the crust, upper mantle, and lower mantle. On this base, the geodynamics background and mechanism in an area of the China Seas (25 degrees N similar to 42 degrees N, 118 degrees E similar to 130 degrees E) are studied. The evidence shows gravity anomaly of different degree in the study area is mainly due to mass distribution of different depth, and the dynamical imbalance from the geopotential imbalance should be responsible for global dynamics activities, which change the lithosphere structure through mantle circulation.