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DES Home > EMQ Home > Community Safety and Sustainability > Earthquakes

Earthquakes

Earthquakes are a shaking or trembling of the Earth's crust caused by the release of huge stresses due to underground volcanic forces, the breaking of rock between the surface, or by a sudden movement along an existing fault line.

Earthquakes are unpredictable and strike without warning. They range in strength from slight tremors to great shocks lasting from a few seconds to a few minutes.

The magnitude of (or energy released by) an earthquake is recorded by a siesmograph using the Richter Scale. There is no upper limit to this scale as there is no upper limit to the amount of energy an earthquake might release. The most severe earthquakes recorded so far have not exceeded 9.5 on the Richter Scale.

History

Australia's worst earthquakes

In the last 80 years there have been 17 earthquakes in Australia registering 6 or more on the Richter Scale.

Australia's rate of earthquakes is about 1 every 5 five years, compared to a world average of about 140 per year.

Most earthquake casualties result from falling objects or debris because shocks can damage or demolish buildings and other structures.

Electricity and telephone lines, gas, sewer and water mains can be damaged; landslides, faults, subsidence and even tsunamis (huge seismic waves) can be caused leaving many people dead, injured or homeless.

The first recorded (indirect) deaths caused by an earthquake occurred in 1902 at Warooka in South Australia when two people died of shock, and in 1917 one miner died and 5 were injured in an underground rockfall triggered by an earthquake at Kalgoorlie, WA.

Newcastle, NSW (1989) - An Australian Case Study

At 10:27am on 28 December 1989, Newcastle (Australia's 6th largest city) was partially devastated by a moderate earthquake measuring 5.6 on the Richter Scale.

Newcastle was the first 'lethal' earthquake in Australia claiming 13 lives and injuring 150 others. It caused extensive damage to about 35,000 homes and 3,000 buildings with 70,000 buildings in the regions suffering some form of damage.

Insured losses reached $1,124 million while the estimated total damage to Newcastle was $4,480 million.

Newcastle showed that a lethal earthquake can occur in parts of Australia considered to be of low seismic risk. It has resulted in improved building codes and practices, and closer monitoring of seismic activity.

Since 1994 all buildings in Australia (including homes) are now required to be constructed to resist earthquakes.

Know your local earthquake risk

What you should do

Watch for possible warning signs

When an earthquake hits

After an earthquake

Further information about earthquakes

Queensland University Advanced Centre for Earthquake Studies

Seismology Research Centre

Geoscience Australia: Earthquake Information

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Last updated 18 December 2011