The Australian Stress Map

Abstract

Knowledge of the in situ stress field of the Australian continent has increased greatly since compilation of the World Stress Map in 1992, principally by analysis of borehole breakouts and drilling-induced tensile fractures in petroleum wells. Stress orientations are variable across the Australian continent as a whole. However, within 15 of 16 individual stress provinces defined in the Australian continent (of one to a few hundred kilometres scale), mean stress orientations are statistically significant. The stress provinces, and stress trajectory mapping, reveal that there are systematic, continental-scale rotations of stress orientation within Australia. Unlike many other continental areas, stress orientations do not parallel the direction of absolute plate motion. Nonetheless, the regional pattern of stress orientation is consistent with control by plate boundary forces, if the complex nature of the convergent northeastern boundary of the Indo-Australian plate, and stress focusing by collisional segments of the boundary, is recognized.