How frequent are Earthquakes?

The above graph shows the natural scale of earthquake magnitude vs frequency. As you can see the stronger the earthquake, the less frequent they occur. In Adelaide, and the SA area, earthquakes are rarely felt unless they are above a level 4 or 5. In 1954 there was a magnitude 5.4 earthquake which hit Adelaide, causing damage and some serious injury. Seismologists predict that the Adelaide region is due for another similar strength earthquake in the coming years. Due to the size of Australia, a magnitude 6 earthquake occurs somewhere roughly once every five years – but the chance of them the epicenter being in a heavily populated area is a lot lower. Earthquakes with a magnitude greater than 8 generally only occur at plate boundaries.