Abstract: From the analysis of the distribution of strong earthquakes, the deep-seated crustal structures and the medium conditions, the authors of this paper attempt to divide the faults within the earth's crust into six groups and to estimate the depth and characteristics of seismo-pregnant layers. The motion of upper mantle materials, the faulting and seismicity are a common source-contemporaneous. The occurrence of strong earthquakes is directly controlled by the activities of both deeply penetrating faults and faults of basaltic layers.