The Australian stress map

Knowledge of the in situ stress field of the Australian continent has incre ased greatly since compilation of the World Stress Map in 1992, principally by analysis of borehole breakouts and drilling-induced tensile fractures i n petroleum wells. Stress orientations are variable across the Australian c ontinent as a whole. However, within 15 of 16 individual stress provinces d efined in the Australian continent (of one to a few hundred kilometres scal e), mean stress orientations are statistically significant. The stress prov inces, and stress trajectory mapping, reveal that there are systematic, con tinental-scale rotations of stress orientation within Australia. Unlike man y other continental areas, stress orientations do not parallel the directio n of absolute plate motion. Nonetheless, the regional pattern of stress ori entation is consistent with control by plate boundary forces, if the comple x nature of the convergent northeastern boundary of the Indo-Australian pla te, and stress focusing by collisional segments of the boundary, is recogni zed.