I believe they are officially dormant, although each specific volcano will not erupt again. There are a large number of volcanoes in south west Victoria which last erupted about 10,000 years ago. There are no large extinct volcanoes as there is something like an area of volcanic instability and as the our continent passes over this area new volcanoes pop through occasionally causing many small volcanoes.
Mt Nootat has the best defined cone as many blew out the side, remained full or were much smaller.
