The Phu Khanh Basin is a north to south elongated, approximately 300km long and 100km wide, extensional basin. It lies in approximately 20-2,500m of water in the Vietnam continental shelf area, which comprises a series of Cenozoic sedimentary basins, located within a transitional zone from the continental crust of the Indochina Craton to the oceanic crust of the South China Sea. The Phu Khanh Basin is bounded to the north by the north-east to south-west trending Da Nang Shear Zone, on the east by the steep continental slope of the South China Sea, on the west by the Da Nang Shelf and is separated from the Cuu Long Basin to the south by the north-west to south-east trending Tuy Hoa Shear Zone.