Was there any earthquakes in Australia besides Newcastle?

It is not known what, exactly, caused the Newcastle earthquake of 1989.

Originally, investigations following the earthquake suggested that it was triggered by 200 years of underground coal mining. Geoscientists from Columbia University claimed that removal of 500 mega tonnes of coal and 2000 mega tonnes of water removed from the ground reactivated a major faultline underneath the Newcastle's coalfields. Removal of millions of tonnes of coal, and the pumping out of water needed in the mining process, created enough stress to reactivate a fault line beneath the Newcastle coal fields.

However, a 2007 report cast doubts on this theory, which came from a US report. Australian geoscientists believe more factors were involved, as evidenced by the fact that minor earthquakes have occurred in the Hunter Valley coal mining region from time to time, and not necessarily close to the coal mining sites. The epicentre of the quake was simply too far underground to have been caused by coal mining alone.

For more details on possible causes of the Newcastle earthquake, see the link below.