GA has changed their interpretation in this map made ~615pm NSW time
Unless there was a close network of seismographs in the district - these maps are a bit of an art form -
I see the USGS has the epicentres - 4.4mag 4.48 km N of Denman -- and the 4.8mag 14km East of Denman
It can not be exceptional getting minor quakes in areas where the crust is disturbed by mining - But magnitudes near 5 are noteworthy.
unloading the crust around open cuts then adding loads where waste piles are built.
Then a detailed knowledge of the local geology would assist understanding.
It is possible too that earthquake scarps may yet be reported on in the landscape which would aid in pinning down exactly what moved..
