Possible influence of static and viscoelastic stress perturbations in Musgrave block (Central Australia) earthquake sequence

Abstract

The spatial and temporal distribution of earthquakes inside continental interiors, where tectonic loading rate is negligible, is much more complicated than plate boundary regions. On 30 March 1986, the moment magnitude (Mw) 5.7 Marryat Creek earthquake occurred in the Musgrave Block of central Australia. Subsequent earthquakes include the1989 Ml 5.6 Uluru, 2012 Mw 5.2 Pukatja, 2013 Mw 5.6 Mulga Park, and 2016 Mw 6.0 Petermann earthquakes. In this study, I explore whether coseismic and viscoelastic Coulomb stress changes following the 1986 Marryat Creek earthquake could have played a role in influencing the basic spatiotemporal characteristics of this earthquake sequence. I find that coseismic stress change does not successfully explain earthquake triggering in the area. I then explore this issue using a viscoelastic stress change model with a range of rheology parameters. In some models, the magnitude of viscoelastic stress change is higher than coseismic stress changes and may be of sufficient magnitude to be considered within an earthquake triggering context. Moreover, I also hypothesize that these earthquakes may have occurred due to dynamic stress triggering or other processes such as fluid migration, nonlinear friction, and/or aseismic deformation, which due to the small distribution of seismic networks across the area I have not been able to investigate in detail. However, I cannot dismiss the possibility that these earthquakes occurred randomly, with no identifiable stress triggering relationships among them.