Australian Earthquakes in 2001
20 December 2001
Most Australians don't consider that they live in an earthquake prone area. We are unlike New Zealand or California, which seem to shake on a regular basis.
But the reality is that Australia does live under the constant threat of earthquakes and they are of magnitudes that have the potential to injure people and damage property. It is the role of Geoscience Australia to monitor these earthquakes.
Over the last 12 months there have been 201 earthquakes with a magnitude greater than 2.5 in Australia, the largest of which was magnitude 5.2 near Ravensthorpe, Western Australia. On average there are about four earthquakes a week which may be felt.
In comparison, there were 157 earthquakes in 2000 with magnitude greater than 2.5. The largest occurred at Boolarra in Victoria with a magnitude of 5.0.
While the overall level of seismic activity is low compared to other countries, Australia still feels on average an earthquake of magnitude six or greater every five years and a two to four magnitude five earthquakes every 12 months.
There have been damaging earthquakes in Australia's recent past. In 1989, a magnitude 5.6 earthquake killed 13 people in Newcastle and caused around $1.5 billion of damage. In 1988 three earthquakes, all with magnitude greater than 6.0, shook the town of Tennant Creek and cut the gas pipeline running to Darwin.
In 1968 an earthquake of magnitude 6.8 occurred in Meckering, WA and caused extensive damage to the town. The largest earthquake to have occurred on the Australian continent in recorded history was located near Meeberrie WA in 1941 and had a magnitude of 7.0.
Australia experiences earthquakes because we are sitting on a huge plate of the earth's crust which is moving very slowly northwards at around 7 cm a year. The movement of the plate causes stresses to build up in the rocks. Occasionally the rocks fracture because of the stress along lines known as faults. An earthquake is the vibration in the earth released when these fractures take place.
Fortunately we don't live right on the boundary of huge crustal plates, for it is here that most the world's earthquakes occur. Countries on the boundaries of crustal plates include New Zealand, Japan and the eastern United States.
Geoscience Australia has a network of seismographs distributed around the country. Data from these instruments is transmitted continuously to Canberra in real-time. Using this network it can provide alerts to emergency management agencies with information about the size and location of potentially damaging earthquakes in Australia and the region.
Aside from the direct effects of ground shaking, another earthquake related hazard is a tsunami caused by large earthquakes on the Australian plate boundary. These earthquakes are also routinely monitored.
While we can't predict earthquakes, ongoing monitoring provides valuable information to help minimise the risk of earthquakes to all Australians.
Topic contact: firstname.lastname@example.org Last updated: May 31, 2012