Tremor may not be last
Wednesday, 24th December, 2014
By Emily Roberts
The earthquake that rocked Broken Hill on Monday night was bigger than first estimated and a warning has been issued that another could strike.
Emma Mathews, a Duty Seismologist at Geoscience Australia, said the earthquake that hit about 10.30pm was a magnitude 3.0. It was originally measured at 2.8 but that was updated yesterday.
“We place an initial reading then it is analysed and confirmed,” Ms Mathews said.
She said earthquakes were caused by underground stress.
“It is due to a build up in the earth’s crust. The stress is then released in the form of earthquakes.
“Across Australia they are called intra-plate earthquakes.
“Earthquakes cluster across certain areas in Australia but they can occur all throughout.”
Ms Mathews said a number of earthquakes are recorded every year in Broken Hill.
“On average the city receives about two earthquakes a year measuring 2.2 to 2.6,” she said.
“The most recent was in July and December of 2011.”
The epicentre of Monday’s quake was 30kms from the city and about 30 Broken Hill locals had reported it, Ms Mathews said.
“We had no reports of damage but locals did report they felt the house vibrating, shaking for 20 seconds and some heard rumbling with rattling windows.”
Ms Mathews said there was a possibility of more earthquakes striking.
“There is a chance another one might occur,” she said.
“It is important to stay vigilant for any possible activity.
“Remember the ‘drop, crawl and hold’ message - drop onto the floor, crawl under cover and hold on.
“It is a natural hazard but people tend to forget protocol.
“I would encourage people to use our website. You can get a lot of information from it.”
The website is: www.ga.gov.au/earthquakes
Perilya moved its underground workforce into safe bays when the earthquake stuck. The General Manager of Broken Hill Operations, Bruce Byrne, was contacted for comment.