While the quake that shook the region on Wednesday, September 22, was the biggest measured earthquake in Victoria's history, the study of geological formations informs us there have been much bigger ones.
Geoscience Australia geologist Dan Clark has investigated the Cadell Fault scarp that extends north-south for 80 km from near Deniliquin in NSW, past Echuca, to Rochester in Victoria.
A series of magnitude 7.3 to 7.5 earthquakes in the period between 20,000 and 70,000 years ago uplifted the western side of the scarp by about 15 m.
This upheaval permanently diverted the Murray and Goulburn rivers.
Australia’s largest river red gum forest, the Barmah forest, formed in the tectonic depression at the foot of the scarp, and so owes its existence to these earthquakes.
