Another chip off the old Australian block

Abstract

Large intraplate earthquakes have an almost universal property of occurring in unexpected places, and on March 30, 1986, the Marryat Creek earthquake confirmed this behavioral pattern. The earthquake took place in central Australia (26.2°S, 132.8°E) in a region that was cratonized in the Early to Middle Proterozoic and that has no record of significant previous seismic activity. The main earthquake had a magnitude of M s ∼5.8 and was associated with a surface fault scarp that is in the shape of a boomerang (convex to the northeast) ∼13 km long, with a maximum displacement of 0.8 m. A preliminary fault plane solution for the earthquake indicates that the mechanism was a combination of thrust and strike‐slip faulting, with the pressure axis striking at N 220°E.