The effect of the intermediate principal stress on fault formation and fault angle in siltstone

We conducted true triaxial compression tests on specimens prepared from two siltstone core sections, one above and one below the Chelungpu Fault, Taiwan. For different constant σ2 and σ3 magnitudes, the maximum principal stress (σ1) was raised until a post failure stage was reached, and a through-going fault had developed. Despite differences between the properties of the two cores, in all tests peak σ1 increased as σ2 was set at higher levels...