© Google
The green dot indicates where the quake struck at a depth of 17 kilometres
Officials in the New England region of the Australian state of New South Wales are breathing a sigh of relief, with no major damage found from two earthquakes that hit on Friday night. Residents were shaken when two magnitude-4.2 quakes hit within a few minutes of each other.

More than 400 people have reported feeling tremors or hearing loud noises. Many called police because they thought they were being robbed. Gunnedah Shire Mayor Adam Marshall says he has never heard of a tremor in the region before.

"I guess no-one's really thought about checking their insurance policy for anything like earthquake damage," he said. But there have been no reports so far of damage beyond a few windows in need of replacement.

Resident Jeff Silvey says it sounded like a jumbo jet and it set off dogs barking all along his street. "I thought it was just a jumbo jet but then everyone else started texting saying no it's an earthquake," he said. "The whole house shook and all the windows and even the dogs got scared - we had to bring the dogs in."

The tremor was felt by residents as far away as the coastal town of South West Rocks, more than 200 kilometres from the quake's epicentre."I was in a rather soft chair, which sort of surprised me that I felt it," resident Ken Shingleton said.

Geoscience Australia has warned there is a high chance of weaker aftershocks in the coming weeks.

Jonathon Bathgate, a seismologist with Geoscience Australia, says the New England region has had a few earthquakes in the past 100 years.

"There's been about 13 of this sort of magnitude in that area in these sort of times," he said.

Mr Bathgate says it is all to do with the underground plates Australia sits on.

"The continent's moving north at about seven centimetres every year and that just builds up stresses across the rocks. So the overall process is the same for big earthquakes," he said.

"We can't predict earthquakes but generally what happens with earthquakes of this size is there is some aftershock activity just as the fault that has moved in an earthquake it sort of resettles down, you'll get some smaller tremors and a lot of those will go unnoticed by the public."

[Editor's note: USGS data]