Queensland may have minor fault lines

Large earthquakes on the Australian mainland are rare but
seismologists are monitoring the development of what could be minor fault lines
in north Queensland.

Since the beginning of the year, a number of quakes have rattled the region
from Innisfail to Mackay.

Geoscience Australia says it has been watching every movement in the last
month to see if it points to a significant shift in the plates beneath
Australia.

A team from Geoscience Australia has installed specialised equipment around Bowen to record every single aftershock since an earthquake in the region in April.

The epicentre of that earthquake was west of Bowen with a magnitude similar
to a quake that damaged a city in southern Spain earlier this month.

“We’ve currently got some temporary aftershock recorders at four sites
south-west of Bowen,” Geoscience team member Emma Mathews said.

“The aftershocks that we’ve recorded on the permanent stations – there’s
approximately seven.”

Ms Mathews says a one-off quake on the Australian plate is usually followed
up by many more smaller shakes.

“Generally earthquakes tend to occur in clusters around Australia,” she
said.

“You get sort of phases of activity depending on the stresses that build up
and the release of those stresses. And this seems to be one of those
examples.”

But Ms Mathews says the number and magnitude of these tremors suggest new
minor fault lines are forming near Bowen.

“They don’t occur on subduction zones or plate boundaries like in New Zealand
or Japan,” she said.

“We have them on the inside of the plate and this is related to stresses that
build up in the tectonic plate.

“We’ll have to wait and see what the data says before we can declare that
there’s a new fault line up there.”

http://www.abc.net.au/news/stories/2011/05/23/3224636.htm

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