Since 1900 the Asian intracontinental great earthquakes (M≥8.0) mainly have distributed in the three boundary zones of a vast triangle-shaped area, in addition, within this area the seismic activities are rather strong. The three boundary zones in turn are as follows: the Himalayas, the mountainous regions from Pamirs to West Mongolia, and the North-South Tectonic Belt in China. The author terms this area as the Asian Intracontinental Triangular Seismic Area (AITSA).
Based on the characteristics of the lithosphere thickness, the values of Vpn, the distribution of the upper mantle density, the isostatic gravity anomalies, the crustal structure, recent tectonic movement and seismic activities, the author infers preliminarily that, under the action of the gravity force, beneath AITSA there exists multi-diapirism from asthenosphere. Owing to this process of the upper mantle materials, the thinning of the lithosphere as result of erosion and the thickening of the crust clue to accretion may take place. the thickened crust is in a state of gravitational instability, resulting in the crustal materials flow, which controls the recent tectonic movements and the seismic activities within the crust.
According to this paper, the gravity may be the major one of the un-negligible tectonic driving forces in the AITSA.