Australia's biggest shake in 15 years

24 March 2012

A magnitude 6.1 earthquake occurred near Ernabella, a remote South Australian aboriginal community about 320km south west of Alice Springs, at 8:25pm AEST on 23 March.

"This is the largest earthquake to have shaken Australia in 15 years. An earthquake of this size has the potential to cause minor damage to nearby communities, but we have not had any reports of damage so far. It was likely to have been felt as far away as Alice Springs, Coober Pedy and Oodnadatta," said Seismologist, Dr David Jepsen.

"There have been numerous aftershocks, the largest one measuring magnitude 3.4. While we expect these to continue, they will drop off in magnitude and frequency over time'" Dr Jepsen said.

"This is the third earthquake in the area over the past week - a magnitude 4.3 earthquake on 16 March, followed by a magnitude 3.8 on 20 March.

"These intra-plate earthquakes occur due to the release of stress that has built up in the Earth's crust, caused by movement of the tectonic plates. The Australian continent is part of the Indian-Australian plate which is being pushed slowly north-east at approximately 7cm per year. South Australia is being slowly squeezed sideways by about 0.1mm each year.

"On average, there are about 200 earthquakes of magnitude 3 or more in Australia each year. Earthquakes above magnitude 5.5, such as the 5.6 magnitude event in Newcastle in 1989, occur on average every two years. Earthquakes of a magnitude 6 or greater are much less frequent. The largest earthquake in Australia occurred in 1941 in Meeberrie, Western Australia, estimated at a magnitude of 7.3," said Dr Jepsen.

As a part of the Australian Government's Administrative Orders, Geoscience Australia has a role in monitoring, analyzing and reporting all earthquakes that can be located in Australia, as well as any significant earthquakes occurring overseas.

The agency monitors seismic data in near real time on a 24/7 basis, using data from over 60 stations on the Australian National Seismic Network and over 130 stations worldwide. The seismic data is delivered by various digital satellite and broadband communication systems to the agency's central processing facility in Canberra.

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