1. The fundament surface varies quite complicatedly from exposal on the surface to the depth of 7-9 km: in Northwest Vietnam-Pha Long region can reach the depth of 7-8 km; Northeast Vietnam region has weak variation of crystallized fundament (2-6 km); Truong Son region crystallized fundament surface varies from exposal on the surface to depth of 5-6 km; South Vietnam has the feature of crystallized fundament surface varying quite complicatedly from exposal on the surface to depth of 4-5 km; Phu Quoc zone (4-5 km).
2. Transitional crust region of East Sea margin has quite big thickness of Cenozoic sediments, varying in the limit from 2-3 km to 13-14 km. Making up this sediment crust are basins with big depth, which have the biggest prospect on oil in the territory of Vietnam. Broken quaternary sedimentary coverage in the area of new oceanic crust region has thickness of less than 1 km.
3. In general, the depth to the M-discontinuity is about 14 - 38 km. This discontinuity has tendency to increase its depth northwestward and in central part of Mesozoic folded regions and in ancient geo-blocks or platform, and decreases in the Cenozoic folded zones, such as Vietnam East sea plate, rifting depressions and basins.
4. The average P wave velocity of Viet Nam territory and adjacency of the main layers of the lithosphere are the follow: for lower crust, P = 5,92 - 7,60 km/s2; for upper mantle, P = 7,85 - 8,00 km/s2; for asthenosphere, P = 8,00 - 8,20 km/s2; for transition zone (from the depth of 450-470 km to 650 km), P = 9,50 - 10,50 km/s2; and the lower mantle has the P equals 10,80 - 10,95 km/s2.