STRESS STATE IN THE UPPER CRUST OF THE CHINA MAINLAND

Abstract

The stress state in the upper crust of the China mainland is discussed on the basis of in situ stress data measured by both hydrofracturing and overcoring techniques during the last ten years. From these measurements, it appears that the horizontal stresses are characterized by strong directionality, which varies from region to region. The maximum horizontal shear stress increases linearly with depth and its gradient varies with region. Both the vertical gradients of the maximum horizontal shear stress and the horizontal principal stress are much higher in West China than in East China. Many data show that the direction of the maximum horizontal principal stress, related to the geological structure and recent crustal deformation within the area, is almost uniform over vast regions.