Nguyen Nhu Trung
Hanoi Institute of Oceanography,
Vietnamese Academiy of Science and Technology Vietnam
Satellite gravity is a superb tool for marine tectonic study. It provides a firsthand glimpse into seafloor morphology and tectonic elements such as spreading ridge, offset, continental-ocean boundary, faults, basins, volcanoes, and so on in the ocean. Interpretation of the gravity data constrained by the seismic data is most useful tools for investigating the crustal structure. In this paper, we present the interpretation results of the satellite gravity data constrained by the deep seismic for predicting crustal thickness, fault systems and volcano/magma in the East Sea. Our result shows that the crustal thickness of the East Sea changes in a wide range of 4-31 km. It consists of oceanic and continental crust. The crustal thickness is 31-28 Km along the coast of the northern margin of the Northwestern and Eastern Sub-basins and decreases gradually seaward to 12 Km in the slope. The other side of this sub-basin, the margin is narrow with the crustal thickness of 23-12 Km. In the Southwest Sub-basin, both the margins are wide and thin. The average crustal thickness is about 14-16 km, thicker in the center and thinner surround. The crustal thickness in the northern margin is a little bit thicker than that in the southern margin. The Red River Basin, Phukhanh Basin, Namconson Basin, Tuchinh-Vungmay Basin and Palawan lie thin continental crust (10-12 Km). In contract, Beibuwan Basin, Pearl River Mouth Basin and Cuulong Basin lie in the thicker continental crust (20-24 Km). The thickness of the oceanic crust in the Central Basin is about 4-10 Km, in which the north side of the spreading ridge is thicker than that in the southern side. The results also find that the volcano/magma activities happened in the south side is stronger than that in the north side of the East Sea.