Um, so, on top of all the other apocalyptic nonsense happening across the world and specifically in Victoria today, the state (which has been in lockdown for over 200 days this year) also experienced an earthquake this morning. Which had a magnitude of 5.8. If everything could just stop happening at once right now, that would be great, thanks.

Of course, my first thought upon hearing about the earthquake (aside from feeling left out of all the Twitter memes) was: ‘does Victoria even have earthquakes? Does this stuff even happen here?’. I was shook, you could say.

I don’t remember a lot from primary school science, but earthquakes happening because of tectonic plates clashing is something that I do know. And, Australia isn’t on the edge of a tectonic plate. After talking about the earthquake with literally everyone I know, it seems we’re all confused about how this one happened.

Well, don’t worry folks – there is indeed a normal, non-doom-inducing explanation for Victoria’s earthquake, so let’s get into it.

Wait, what exactly is an earthquake?

Not everyone has retained their year six knowledge of tectonic plates as well as I have, so let’s do a quick overview of what exactly earthquakes are.

Beneath the Earth’s crust, we have around 20 huge rocks that are described by NASA to be like “giant puzzle pieces”. These are called tectonic plates, and they constantly shift around and push against each other.

Basically, all that pushing up against each other causes a build up of stress on the crust. Much like me during this pandemic, the crust can only deal with so much pressure — eventually, it’ll crack, as rocks deep below the Earth’s surface break and slip past one another. It’s this sudden release of energy that causes an earthquake.

But don’t only places like Japan or New Zealand get earthquakes?

Up until today, I too mostly associated earthquakes with places like Japan, because those places lie on the edges of tectonic plates, where all that tension is going on. These are the places we hear about in the news.

Australia, though, is in the centre of a tectonic plate – so how do we also have earthquakes? And how did Victoria have one so big?

When I was in school, we were taught about tectonic plates with the pencil metaphor — if you have two pencils, and push their ends together, the ends will splinter and fray, right? Which explains how the edges of tectonic plates push against each other and cause breakage and stress.

Well, if you have one pencil, and push at both its ends with enough force, you can cause a crack down the centre, too. Which is how we get earthquakes in the centre of tectonic plates.

The ABC spoke to Dr Trevor Allen, a seismologist with Geoscience Australia, who explained it in terms of  a pavlova rather than a pencil.

“Imagine if you will, that a tectonic plate is analogous to a pavlova — with a thin brittle crust lying above a ductile, but mostly solid meringue mantle,” Dr Allen told the ABC.

“The Australian continent would sit in the middle of our pavlova.”

The ABC report then went on to explain that if you place pressure on the edge of your pav, the crust around your hands will break first – these are earthquakes at the edges of tectonic plates, like in Japan.

But, if you keep squeezing, eventually strain builds up in the centre of the crust, and cracks will begin to appear. That’s our Aussie earthquakes.

So, is this apocalyptic or not?

This morning’s earthquake was the largest onshore quake ever recorded in Victoria, at a magnitude of 5.8. However, there have been larger earthquakes in Australia as a whole – in 2016, the Northern Territory experienced an earthquake which had a magnitude of 6.1.

According to the ABC, Australia is rocked by an earthquake about once per day already, though they’re just not perceptible to humans. Larger earthquakes, at a magnitude of 5ish, are usually only seen once or twice a year.

Australia actually has an earthquake of magnitude 6 or higher every six to 10 years, according to seismologists who wrote about Victoria’s earthquake for The Conversation.

As for the more devastating earthquakes of a magnitude of 8 or 9 — those happen on the edges of tectonic plates, and we’re pretty unlikely to experience them here in Australia.

So, no, this particular earthquake wasn’t a freak event – this stuff just happens sometimes. Though during a time where we’re all dealing with a bunch of other stressful events – a global pandemic, climate change, etc. – it definitely feels like A Lot™.

Regarding today’s tremors, there’s likely to be some aftershocks we might feel in the aftermath. You can read about how to protect yourself from an earthquake here.