Fortnight of 119 quakes

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 hit off Albany, 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.”