A small, 2.4-magnitude earthquake struck an outer Melbourne suburb on Wednesday morning.
While a minor event, it was Victoria’s third recorded earthquake in less than two months.
Why is Melbourne having earthquakes?
The recent earthquakes in Victoria aren’t totally unusual, according to Dee Ninis, an Earthquake Geologist at the Australian Seismology Research Centre and Monash University.
Ninis told TDA that 40-60 earthquakes are recorded in south east Australia on any given week, but most of these can’t be felt or are in remote regions.
“It feels like there have been a lot [recently], but what’s happened is they’ve just by chance been just big enough… and right under Melbourne.”
Ninis said the exception to this was the 4.6-magnitude earthquake that struck the Victorian town of Rawson last week.
This was an ‘aftershock’ earthquake – a smaller one that’s part of the fault lines readjusting – from a 5.9-magnitude earthquake in 2021.
Ninis said Victoria is particularly affected by plate boundaries on the Pacific Ocean, which increases the possibility of an earthquake.
Southeast NSW, northern Tasmania, and the top and bottom parts of Western Australia are also particularly susceptible to earthquakes.
What causes an earthquake?
Earthquakes are caused by activity between tectonic plates.
Tectonic plates are what make up the sections of the Earth’s crust. This is the planet’s outermost shell that we all stand and walk on.
Tectonic plates slowly and continually move against each other, which builds up stress. An earthquake occurs when the stress created from movement between plates is finally released.
Devastating earthquakes generally occur on fault lines – this is where two tectonic plates meet. There are fault lines running through New Zealand, California, and the Caribbean.
This has caused some extreme earthquakes, such as the 2011 Christchurch earthquake and the 2010 Haiti earthquake.
Is another one coming?
Ninis said that future earthquakes can’t be predicted.
It’s also difficult to understand the sequences of earthquake activity. For example, it’s possible that the earthquake recorded this week could be a ‘foreshock’ for a later, more powerful one to come.
However, Ninis said the chance of a bigger earthquake in Victoria, including one closer to Melbourne, “hasn’t increased” in the wake of recent tremors.