Palaeoseismicity

In geological terms, the settlement of Australia is very recent - only just over 200 years ago. The number of very large earthquakes in Australia in that period is very low, relative to what must have happened in say the last 1000 years. If large earthquakes which occurred before settlement can be located and dated, then this gives useful clues as to where large earthquakes might strike again.

Large pre-historic earthquakes are often identified from aerial photography, by examining areas where streams or rivers may have been ponded by sudden elevation changes, or by the examination of scarps in areas where they may not have been expected.

Places in Australia where prehistoric fault scarps have been identified are

• Hyden, WA
• Lort River, near Ravensthorpe, WA
• Merredin WA
• Mt. Narryer, WA
• Lake Edgar, Tas
• Cadell Fault, NSW
• Snowy Mtns., NSW
• Avondale, Vic
• Palmer Fault, SA, near Adelaide
• Middlebank Ra., SA

The fault scarp at Hyden was trenched by scientists from UWA and GA in 1991. The trenching indicated that the scarp was formed by one or two large shallow earthquakes, of at least magnitude 6.0

Below - Aerial photograph showing the Hyden Fault Scarp.