Source and Attenuation Properties of the 2012 Moe Earthquake Sequence, Southeastern Australia

The local magnitude ML 5.4 (MW 5.1) Moe earthquake on 19 June 2012 that occurred within the Australian stable continental region was the largest seismic event for the state of Victoria for more than 30 years. Seismic networks in the southeast Australian region yielded many high-quality recordings of the moderate-magnitude earthquake mainshock and its largest aftershock (ML 4.4; MW 4.3) at a hypocentral range of 10 to 480 km. The source and attenuation characteristics of the earthquake sequence are analyzed. Almost 15,000 felt reports were received following the main shock, which tripped a number of coal-fired power generators in the region, amounting to the loss of approximately 1955 megawatts of generation capacity. The attenuation of macroseismic intensities are shown to mimic the attenuation shape of Eastern North America (ENA) models, but require an inter-event bias to reduce predicted intensities. Further instrumental ground-motion recordings are compared to ground-motion models (GMMs) considered applicable for the southeastern Australian (SEA) region. Some GMMs developed for ENA and for SEA provide reasonable estimates of the recorded ground motions of spectral acceleration within epicentral distances of approximately 100 km. The mean weighted of the Next Generation Attenuation-East GMM suite, recently developed for stable ENA, performs relatively poorly for the 2012 Moe earthquake sequence, particularly for short-period accelerations.