What is seismic activity in Australia?

Seismic activity in Australia is the term for earthquakes and related ground movement caused by tectonic plate movement, fault slips, and stress accumulating within the rock. Australia is one of the lower-risk earthquake regions in the world because it sits in the middle of the Indo-Australian Plate, far from any active plate boundary.

Geoscience Australia records around 100 earthquakes a year of magnitude 3 or above, but most are too small to be felt. Magnitude 5 events occur a few times a year, magnitude 6 events about every five years, and magnitude 7 events very rarely. The largest recorded onshore Australian earthquake was the magnitude 6.6 Tennant Creek event in 1988, in the Northern Territory, which produced a 35-kilometre-long surface rupture.

Notable damaging earthquakes in Australian history include the magnitude 5.6 Newcastle earthquake on 28 December 1989, which killed 13 people and injured more than 160 in the only fatal Australian earthquake in over a century; the magnitude 5.4 Mansfield earthquake of 22 September 2021, the largest ever recorded in Victoria; and the magnitude 6.5 Meeberrie earthquake of 1941, the largest in Western Australia. The Mansfield event was felt across Melbourne and prompted updates to building-code expectations for non-residential buildings.

Tsunamis from large earthquakes in the Indonesian and Pacific subduction zones can affect Australia. The 2004 Indian Ocean tsunami caused damage at Geraldton and Christmas Island. The Australian Tsunami Warning Centre, operated by the Bureau of Meteorology and Geoscience Australia, monitors for tsunami threats. Building codes across Australia include earthquake-loading provisions under the National Construction Code, with risk levels calibrated for each region. South Australia and parts of inland Western Australia carry slightly higher risk than the rest of the country.