The earthquake that hit Melbourne's north-west fringe on Sunday night was stronger than originally thought.
Geoscience Australia said on Tuesday that it had upgraded the quake from magnitute-3.8 to magnitude-4, and also revealed there was an aftershock of magnitude-2.6 just two minutes after the main jolt.
More than 26,000 people in an area stretching from Albury in the state's north down to Hobart have now reported they felt the effects of the quake at the time.
The earthquake hit at 11.41pm on Sunday, as most Melburnians slept, and was centred on the outer suburb of Sunbury.
Although it was not particularly strong, the comparatively shallow depth at which it occurred meant it was felt more widely than would be normal.
While most Australian earthquakes are generated around 10 kilometres underground, the Sunbury quake was far shallower, around 3 kilometres below the surface.
Geoscience Australia says nationally, there is an earthquake above magnitude-5 every one to two years.
Potentially damaging earthquakes of magnitude-6.0 or above happen about every 10 years.
Despite the upgrading of the Sunbury earthquake, it still lags significantly behind the 2021 quake centred in the small Victorian town of Rawson.
The Rawson earthquake was measured at magnitude-5.9 and felt from Sydney to Hobart, west to Adelaide and, of course, in Melbourne. More than 43,000 "felt reports" were made in the aftermath of the Rawson quake.
On average, Australia experiences around 100 earthquakes of magnitude-3 or larger each year, according to Geoscience Australia.
Earthquakes above magnitude-5, such as the destructive magnitude-5.4 earthquake in Newcastle in 1989, occur approximately every one to two years.
