oa Seismicity in Northern WA

A new seismic monitoring network installed in northern Western Australia in October 2005 seeks to record low-level seismicity in the region, with a view to understanding event frequency, magnitude, location, geological controls on seismicity and deep-crustal structure that may be contributing to crustal weakness. Data from a network of eight semi-permanent stations, located at localities between Shark Bay and the Dampier area, complements data from an additional 80 stations that were deployed for shorter periods as part of other research projects at the ANU between 2000 and 2006. This dense network of seismometers provides the opportunity for a detailed analysis of seismicity and shallow- and deep-crustal structure in the northwest of WA.

For events such as the M5.3 event in Shark Bay in February 2007, our network provided the detailed data required for accurate location and potential fault plane solutions. Potential fault plane orientations have significant implications for our understanding of the neotectonic evolution of this part of Australia, and mechanical contrasts in the crust that may be predisposing areas to failure. Despite the region hosting large earthquakes (Geraldton, 1885, M6.5; offshore WA, M6.2, 1920), including Australia’s largest known event (Meeberrie, M7.3, 1941), little is known about the frequency, magnitude or causes of seismicity in this region, which is far less known than the SW Seismic Zone.

This project is part of an Australian Research Council Linkage project hosted at The University of Western Australia and involving collaboration with The Australian National University and Geoscience Australia, sponsored by Woodside Energy.