More tremors may follow Melbourne quakes

Further earth tremors are likely following a 4.5 magnitude earthquake that shook
Melbourne and eastern Victoria on Wednesday.
The quake, the second felt by Melburnians in the past 12 days, occurred about 5km
northeast of Korumburra, 100km southeast of Melbourne, at 4.28pm (AEDT).
The epicentre is in the same area of an earthquake with a magnitude of 4.6 on the
Richter scale that hit on March 6.
Wednesday's quake was felt across metropolitan Melbourne as far away as Bacchus
Marsh, 50km west of Melbourne.
Geosciences Australia duty seismologist Steve Tathum said the event was one of five
significant tremors centred on the same area near Korumburra in the past 12 days.
"Because this event has an equal magnitude to the March 6 quake it's not correct to
say it is an aftershock. It's a significant event and you could say the earlier
tremors were foreshocks," he said.
The second quake was one of the largest felt in the Melbourne area for 30 to 40
years, Mr Tathum said.
"We've had hundreds of reports, with people reporting rattling, vibrations, hearing
earth noises or a rumble like a strong wind hitting their roof," he said.
"It's certainly significant but it's not uncommon so people should not worry that
this is anything out of the ordinary."
State Emergency Service (SES) spokesman Alan Briggs said while there had been no
reports of any damage, anyone facing any problems should turn off all gas,
electricity and water and call emergency services.
Eltham resident Caroline Hamilton felt the jolt at her home in Melbourne's northeast.
"I was at home in my living room, sitting on the couch, when I became aware of my
roof shaking like there was a gigantic person up there running around," she said.
"At first I thought the roof was falling in but the floor was shaking too and I
could feel the vibration coming up from under the couch.
"I wouldn't say it was terrifying but it was quite unsettling."
Associate Professor Malcolm Wallace from Melbourne University's school of earth
sciences said the quake was probably an aftershock from the March 6 event.
He said it was normal for smaller tremors to be felt after an earthquake as stress
on fault lines was dispersed from the epicentre.
"If it was from the same area it probably is related to that fairly large one a
while ago," Dr Wallace said.
He said Victorians could expect more aftershocks but it was unlikely the tremor was
a sign of a bigger earthquake to come.
"I don't think it's the prelude to a big earthquake.
"We probably have the same probability now of having a big earthquake as there
always has been."
Dr Wallace said large earthquakes had not occurred in Victoria for thousands of years.
And while there was a possibility Victoria would again be hit by a big earthquake it
was impossible to predict.