Many Vietnamese and foreign geologists subdivided the VÜnh Linh – Cån Cá basalt activities into 3 stages: Pliocene-Early Pleistocene, Middle Pleistocene-Late Pleistocene and Holocene with two types of typical eruption: the fissure effusion and the central eruption. But in some works, the authors considered that there is no Holocene basalt in the VÜnh Linh – Cån Cá area. The seismic analysis results of high resolution of the sea floor have proved that Quaternary basalt activities are very complicated in this area. They may be divided into 6 phases: Q₁¹, Q₁^2a, Q₁^2b, Q₁^3a, Q₁^3b and Q₂. Every phase was related to the beds of Quaternary sediments. This was the penetration of older sediment layers, and the erosion by trangression phase of the next sedimentary cycle. The fissure effusion type occurs in the first stage of Quaternary, as the eruption type - in the later stages.