Six aftershocks have since been registered, between 2.4 and 4.1 on the Richter scale, and further tremors are expected in coming days and possibly months.
"What we have seen as a result of the 5.9 earthquake that affected Victoria today is a range of minor structural damage," State Emergency Service chief officer Tim Wiebusch told reporters in Melbourne.
"We have had just over 100 requests for assistance, 55 in the metropolitan area, largely related to minor structural damage to chimneys and facades on buildings."
State Emergency Service chief officer Tim Wiebusch said it was "fortunate" the epicentre of the quake happened in a largely unpopulated part of regional Victoria.
"If that had occurred in one of our more urban and populated areas, we could be seeing quite a different result," he told reporters.
No major structural issues have been found after checks of rail lines, roads and dams.
Some building damage has emerged in metropolitan Melbourne and areas near Mansfield, with Beechworth hospital losing power and the cross at St Patrick's Church in Wangaratta falling down.
Among the buildings damaged is the facade of a Fitzroy building on Brunswick Road and the exterior of Betty's Burgers on Chapel Street in Windsor.
Movement was also felt in Geelong, at Canberra's Parliament House, Sydney's CBD, northern Tasmania and parts of South Australia.
More than 46 reports of building damage after Victoria earthquake
Victoria’s Deputy Premier James Merlino said Geoscience "has confirmed that there is a possibility that we may receive further aftershocks" and there was a potential risk of more earthquakes.
“Indeed, more aftershocks could occur for weeks, if not months," he told reporters in Melbourne.
The mayor of Mansfield, Mark Holcombe, said the quake was unlike anything he's experienced before in his 20 years living in the town.
"I was sitting down at work at my desk and I needed to run outside. It took me a while to work out what it was," he told the ABC.
"I have been in earthquakes overseas before and it seemed to go on longer than I have experienced before. The other thing that surprised me was how noisy it was, it was a real rumbling like a truck going past."
The Bureau of Meteorology said there was no tsunami threat.
Scott Morrison speaks after earthquake in Victoria
Speaking from the United States after being briefed about the earthquake, Prime Minister Scott Morrison said the federal government stands by “to provide whatever assistance is needed, whether from the [defence force] or others”.
It's understood the earthquake is one of the strongest ever to hit Australia.
A magnitude 5.6 earthquake in Newcastle in 1989 left 13 people dead.