The state of Victoria, Australia, was shaken by its biggest onshore earthquake in recorded history on 22 September. Some buildings were damaged but no one was seriously hurt.
The magnitude 5.9 earthquake struck at 9:15am local time, according to Geoscience Australia. The epicentre was in the Alpine National Park about 120 kilometres east of Melbourne, at a shallow depth of around 10 kilometres.
People in Melbourne, who are currently in a covid-19 lockdown, reported feeling the ground shake for 15 to 20 seconds. Tremors were also felt in Canberra, just over 300 kilometres north-east of the epicentre.
A small number of buildings in Melbourne partially collapsed and power outages occurred in some parts of the city, but no major damage or serious injuries have been reported.
This is thanks to the epicentre occurring in a relatively remote region, says Dee Ninis at the Seismology Research Centre in Melbourne. “We’re really lucky it wasn’t in a populated area,” she says
Australia experiences relatively few earthquakes because it sits in the middle of a tectonic plate, says Meghan Miller at the Australian National University in Canberra. “Countries like New Zealand, Indonesia and Japan are more at risk because they sit on plate boundaries,” she says. “But it is a common fallacy that earthquakes don’t happen in Australia.”
One of Australia’s worst earthquakes was a magnitude 5.6 earthquake in Newcastle in New South Wales in 1989, which caused extensive damage and killed 13 people.
Earthquakes occur in Australia when the tectonic plate that it sits on rubs against others and stress is slowly transmitted through the plate, eventually leading to a pressure build-up that causes a fault within the plate to rupture, says Phil Cummins, also at the Australian National University.
A magnitude 5.7 earthquake occurred in a similar region of Victoria in 1966, suggesting it may be an area that is prone to rupturing when stress gradually builds up, says Cummins.
A magnitude 4.1 aftershock was recorded 15 minutes after this morning’s earthquake, but Cummins expects there will be no more big aftershocks. Australia’s Bureau of Meteorology has also deemed that there is no tsunami risk.
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