Albany Extra - - Front Page - Toby Hussey

Great South­ern rat­tled by more than 100 tremors in past fort­night, cen­tred around Lake Muir.

Geo­science Aus­tralia has recorded 119 earth­quakes in the re­gion around Lake Muir in the past two weeks, in­clud­ing 80 last week­end.

Tremors be­tween 0.1 and 5.7 mag­ni­tude were recorded from Septem­ber 13 to Septem­ber 27, densely dot­ting the area east of Lake Muir on the Fran­k­land River, about 50km north of Walpole

These in­cluded the big­gest earth­quake in 20 years, a 5.7 mag­ni­tude mon­ster which shook homes across the South West and was felt as far north as Perth.

Geo­science Aus­tralia seis­mol­o­gist Dan Jaksa, speak­ing when just 18 earth­quakes had been recorded, said the re­cent clus­ter­ing of earth­quakes around Lake Muir was un­usual.

“It’s cer­tainly new for this area, this part of WA has never re­ally been that ac­tive,” he said.

Mr Jaksa said the tremors were the re­sult of tec­tonic col­li­sions thou­sands of kilo­me­tres from Al­bany. “We’re a quick-mov­ing con­ti­nent rel­a­tive to the rest of the world,” he said.

“We’re col­lid­ing with the fast-mov­ing con­ti­nent, the Pa­cific plate to the north, and to the east where New Zealand meets the Pa­cific. That im­mense force across the coun­try cre­ates faults that build up stress over time and every now and then the pres­sure has to be re­leased.”

He com­pared the events to a car crash. “In a head-on col­li­sion with a car, the front of the car crum­ples up and in this anal­ogy the crust is the moun­tain ranges (of Pa­pua New Guinea),” he said.

“You might even get cracks in the wind­screen; those cracks are trans­ferred stress from the front through the rest of the car — and the wind­screen is the rest of Aus­tralia.”

Eighty earth­quakes were recorded on the week­end. Each dot on this map rep­re­sents one earth­quake.

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