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Geoscience Australia monitors, analyses and reports on earthquakes within Australia and internationally. This is done on a 24/7 basis by Duty Seismologists for the purposes of tsunami warning as part of the Australian Tsunami Warning System (ATWS) and to alert the Australian Government, State and Territory Governments and the general public of earthquakes in Australia and overseas.

Earthquakes that can be located in Australia are catalogued and published on the Geoscience Australia website. The analysis includes the origin time and date of the earthquake, its hypocentral location (latitude, longitude and depth) and its magnitude. For earthquakes over magnitude 3.5, this can be done by the Duty Seismologist within approximately 30 minutes of the earthquake’s origin time. Smaller earthquakes that are not detected by many seismometers are difficult to locate in real-time and are thus computed by Seismic Analysts later.

Earthquakes outside Australia, but within our region, are published only for earthquakes with a magnitude of 5 or greater. Earthquakes occurring anywhere internationally with a magnitude of 6 or greater are also catalogued and published on the Geoscience Australia website.

As part of the Joint Australian Tsunami Warning Centre (JATWC), Geoscience Australia’s Duty Seismologists have the responsibility to analyse and report on earthquakes that have the potential to generate a tsunami within 15 minutes of the origin time. An earthquake alert is then sent to Geoscience Australia’s partner in the JATWC, the Australian Bureau of Meteorology, to determine tsunami advice and publish tsunami bulletins. The earthquake information is also catalogued and published on the Geoscience Australia website.

Why we monitor earthquakes

As a part of the Australian Government’s Administrative Orders, Geoscience Australia has a role in monitoring, analysing and reporting all earthquakes that can be located in Australia and any significant earthquakes occurring overseas.

In the May 2005 Budget, the Australian Government allocated $68.9 million over four years to Geoscience Australia, the Australian Bureau of Meteorology and the Attorney-General’s Department to work on the following policy objectives:

• to provide a comprehensive tsunami warning system for Australia
• to support international efforts to establish an Indian Ocean tsunami warning system
• to contribute to the facilitation of tsunami warnings for the South West Pacific.

In the fifth year from July 2009, a budget was allocated for the ongoing operations of the system. Geoscience Australia’s role in the ATWS is to monitor, analyse and report on earthquakes that have the potential to generate tsunami that may impact Australia.

How we monitor earthquakes

Geoscience Australia monitors seismic data from over 60 stations on the Australian National Seismic Network and over 130 stations worldwide. This is done in near real-time, 24/7, where the majority of the 40 samples per second data is delivered within one minute of its recording at the seismometer. The data is delivered by various digital satellite and broadband communication systems to our central processing facility in Canberra.

Seismic data is also freely provided by overseas Governments who have national seismic networks. Geoscience Australia uses data provided by the Governments of New Zealand, Indonesia, Malaysia, Singapore and China. Data from global seismic networks are also provided by USA, Japan, Germany and France. Seismic data is also provided by the Comprehensive Nuclear Test Ban Treaty Organisation’s International Monitoring System, for tsunami warning purposes.

The seismic data is collected and analysed automatically and then immediately reviewed by Geoscience Australia’s Duty Seismologist. For earthquakes that have the potential to generate a tsunami, preliminary earthquake details are computed within 15 minutes. All other earthquakes are generally computed within 30 minutes.