Revisions to Australia's historical earthquakes

In 2016, Geoscience Australia revised the magnitudes of some of Australia's historical earthquakes as part of an international project to reassess the magnitude estimates of earthquakes around the globe. This project aimed to revise historic earthquake measurements to more accurately reflect their true size based on modernised measuring techniques.

As custodians of Australia's earthquake data, Geoscience Australia has updated information related to Australia's historical earthquakes, resulting in significant changes to what were previously thought to be some of Australia's largest events ever recorded. The following table represents our largest recorded earthquakes* as presented before and after the 2016 revision.

    

Magnitude post-2016 revisions

Magnitude pre-2016 revisions

Location

Date

6.6

6.7

Tennant Creek, NT

1988

6.5

6.9

Meckering, WA

1968

6.4

5.6

Simpson Desert, NT

1941

6.3

6.4

Tennant Creek, NT

1988

6.3

7.2

Meeberrie, WA

1941

6.2

6.3

Collier Bay, WA.

1997

6.2

6.3

Tennant Creek, NT

1988

6.1

6.2

Cadoux, WA

1979

6.1

N/A

Petermann Ranges, NT

2016

6.0

6.0

West of Lake Mackay, WA

1970


* The earthquakes listed above have epicentres on the Australian mainland or adjacent to the Australian coast.

More information about these historical events can be viewed through the earthquake storymap.

The International Seismological Centre led this project which reassessed the location and magnitude of approximately 20 000 historical earthquakes worldwide as part of an effort to extend and improve their database of seismic events.

Frequently asked questions

What does this information add to our understanding of Australian seismicity?

Importantly in the Australian context, this project has seen significant revisions to some of Australia's largest historic earthquakes. This helps us to understand that while the magnitude of some of these Australian earthquakes may not be large when compared with events around the world; they still have significant impact. For example, the Meeberrie Earthquake of 1941 has been downgraded significantly from magnitude 7.2 to 6.3 yet it was felt over a large part of Western Australia. Reports of the earthquake came from Port Hedland in the north, to Albany and Norseman in the south, and even caused minor non-structural damage in Perth - more than 500km from the epicentre.

The largest recorded earthquake is now magnitude 6.6. Is this a good indication of the largest size earthquake we can expect on Australian shores? Or can we experience larger earthquakes, say of magnitude 7 and above like those seen in Haiti and Nepal?

While the revisions mean Australia has not experienced a magnitude 7 earthquake since record keeping began in the late 1800's, there is evidence of multiple earthquakes above magnitude 7 occurring on major faults across the Australian continent over the past 100,000 years. Even then these large earthquakes over magnitude 7 were very rare and occurred thousands of years apart.

How will this information affect our building codes?

Revising the magnitude of historical earthquakes changes our understanding of hazard levels across the country. In other words, it might decrease our estimates of how often earthquakes of a certain magnitude occur in particular regions. Geoscience Australia summarises this information in products such as the Atlas of Seismic Hazard.

The Building Code uses this information as one of various inputs to determine how strong buildings in different parts of the country should be to be sufficiently resilient to likely earthquake events.