Hundreds of people were rattled by a 4.7-magnitude earthquake in WA’s Great Southern at the start of 2022.
The earthquake occurred near Wagin and was the biggest of more than 100 recorded in that region so far this year.
Earthquakes are most closely associated with places positioned on the edge of the Earth’s tectonic plates, like New Zealand or Japan. But the ground beneath Australia’s feet is not as stable as many think – particularly in WA.
On average, Australia records 700 earthquakes a year, occurring all over the country.
WA is the most active both in the size and number of earthquakes. One of Australia’s largest recorded earthquakes tore through the wheat-growing community of Meckering in Western Australia on 14 October 1968.
WA also has several fault lines that are aligned in such a way, compared to the direction the stress is coming from, that it makes it easier for them to crack.
At the time, Geoscience Australia senior seismologist Jonathan Bathgate said there was a ‘little bit of increased activity’ around the Lake Muir quake, with about 600 quakes in the following two months. And WA also gets something known as earthquake swarms far more frequently than other states.
While a usual earthquake pattern involves a main shock and a series of aftershocks, an earthquake swarm involves tens or even hundreds of moderate main shocks, each with its own aftershock.
The basin around Broome, in WA’s north, is another active earthquake region.
Mr Glanville said its proximity to the Indonesian fault line also made that area more susceptible to quakes. Earthquakes above magnitude 5 occur every one to two years, and above magnitude 6 about once a decade, according to GeoScience Australia.
For more information, go to www.abc.net.au/news/2022-02-14/wa-earthquakes-explained/100824390
