Australian earthquake - September 22nd 2021

Today a magnitude 5.8 earthquake has struck about 115 kilometres east of Melbourne in Victoria.
It caused damages to buildings and forced residents to evacuate across the city.

Many LastQuake users reported the shaking through the app and the mobile website. You can see testimonies on this map and read comments here :

Check also this very informative paper: Melbourne earthquake: what exactly happened, and what's the best way to stay safe from aftershocks?

Another interesting update: Making sense of Victoria’s shock earthquake

1 Like

Excellent link thanks! Interesting that the text states the earthquake is the result of the Australia / Pacific plate collision boundary - that is a very long way from Melbourne! Is ir because the Aus plate is very stiff and stresses can be transmitted long distances / activating existing faults associated with the Snowy Mountains (immediately NE of Melbourne)? I noticed many small historical earthquakes on the Seismicity Tab (1960-present), both in the Snowy Mountains and in the S Australia valley to the west (Adelaide area and north). Do these smaller frequent events represent ‘little and often’ stress release, thereby usually avoiding a larger quake (until today!)?

1 Like

It is not necessarily the stiffness, but rather the tipe of interaction between the two tectonic plates that matters. In the case of the Melbourne earthquake, experts say that Australia’s tectonic plate is colliding with the Pacific plate in the Pacific Ocean and that the collision has generated in years and years a build up of compressive stress that, when released suddenly, resulted in the earthquake phenomenon. So, yes, stress can be transmitted activating or sustaining existing faults.

About the second point you raised: these smaller frequent events (‘little and often’) do not necessarily mean that a larger quake might be avoided. Such a subject is unfortunately still under debate within the seismology and geology community.


An interesting piece about seismometers and earthquake measurement tools in Australia : Australia surprised by moderate quake, but rumbling is not unusual -

After living in Japan for many years and experiencing earthquakes of 6.9 and higher, I was very surprised in the shower last week! We live about 12km east of Melbourne city and about 200km south of the epicentre.

I felt more structural shaking than anything in Japan. Thought the roof would cave in. The earth has visibly shifted on our block of land. Our house is on a slope and we are the lowest point in our street. You can visibly see the nature strip has dropped from formerly being flush with the curb, metal storm water grates have bent out of shape and areas of our block are extremely uneven now you can not only feel the lowering of the ground as you walk on it, but also see the earth has lowered as garden beds once flush /covering the foundation slab are now sitting lower and the slab is visible. The only other signs of this are on the street behind us…in front of the house directly behind us. Cracked/broken curb, uneven footpath, nature strip lowered and a small retaining wall of bricks has crumbled/broken.

I also remember feeling an earthquake almost 10 years ago here—but felt more like a heavy truck going down the street.