Earthquake mechanisms in south Australia in relation to plate tectonics

The first comprehensive focal mechanism study of South Australian earthquakes has yielded information on the tectonic stresses operating within the upper crust. A model has been derived for tectonism in the Flinders‐Mt Lofty Ranges which appears to explain some of the major geological features and observed patterns of seismicity. Results support the hypothesis that Australia consists of at least two large quasi‐stable plates, with relative dextral strike‐slip motion in the region of the Adelaide Geosyncline and gulf graben system, which appear to be associated with the plate boundaries. On the basis of present tectonism, an attempt has been made to interpret the past in terms of plate tectonics.