There was an experience of a 5.9 magnitude earthquake yesterday that many Australians were not ready to feel on their skin. Other areas might have large quakes.
The earthquake’s center was at 180km northeast of Melbourne, around a small town called Mansfield. This one was the largest.
In more than 50 years, there was not such a big onshore quake that hit a populated area.
It hit yesterday, but there were no less than 10 aftershocks with magnitude 2.5, including one 4.1 magnitude quake.
Dr. Trevor Allen, the geoscience seismologist, told the news that there were 10 recorded aftershocks, but there were hundreds of smaller aftershocks. They can not be sure of the exact number because there is a limited number of stations in the area. In his opinion, there was ruptured a large area spanning 10km horizontally and 10km vertically.
Even if Australia is not close to any tectonic plates, it has faults that can cause hundreds of tremors every year.
Geoscience Australia developed a map with the exact location of the active faults. The faults moved recently, and they might move again because of the large earthquakes.
Scientists use their knowledge of faults and historical data to predict where earthquakes may occur.
Dr. Allen said that even so, there are things that they can not predict and can be surprising. It should not surprise us that even on low hazards there can be large earthquakes.
Australia has few areas that are potentially susceptible like: South Australia’s Flinders Ranges, Victoria’s Latrobe Valley, and Western Australia.
Faults that are not known yet might be occurred by an earthquake. We have few examples like the quakes around Tennant Creek, Northern Territory, from 1988. Also, there was a 7 magnitude earthquake that divided the course of the Murray River. It leads to the formation of the Barmah Choke.
Dr. Allen said that these earthquakes are extremely rare, but they can occur from time to time. For the quake from yesterday, there had been few historical earthquakes in that area.
He said that the number of large earthquakes in the Eastern Highlands region of southeast Australia is bigger than in Queensland.
Dr. Allen said that one reason was that it was surrounded by faults, including along the Strzelecki Ranges. He said that because of the geological evidence, the faults are young. The ranges will get higher because they are still growing.
