Earthquake Information

What is an earthquake?

Earthquake Predictions

Before an earthquake

During an earthquake

After an earthquake

Measuring an earthquake

More Information

Recent Earthquakes in Australia
SES Earthquake 1

What is an earthquake?

An earthquake is a sudden shaking of the Earth's surface caused by rock breakage deep within the Earth. This is the result of stresses that have built up within the Earth's brittle crust.

There are different types of earthquake, depending on the part of the world in which they occur. Due to Australia's geological position, we are prone to intra-plate earthquakes which have a 'shallow focus'. These earthquakes are different and less predictable than the plate-margin type of earthquake which is common in areas like California, USA and Japan.

Earthquake Predictions

Any part of Australia could experience an earthquake. There is no accepted method to predict earthquakes, however, some regions are more earthquake-prone than others. Parts of South Australia including Adelaide and the mid-north are earthquake hazard areas with a high potential for future earthquakes. Earthquakes are a natural hazard which cannot be prevented but the effect that an earthquake has on your family can be reduced if you have a plan.

Be Prepared

Before an Earthquake Occurs

How to prepare your home:

  • Check that your insurance policy covers earthquake damage and that you are fully insured.
  • If buying a house, consider brick veneer as it is more flexible and earthquake resistant than double brick and stone. For more information regarding this read the Fact Sheet on Earthquakes and House Damage from the Department of Primary Industry and Resources' (PIRSA) website.
  • In existing buildings, check for unsupported masonry parapets, gables and chimneys, and repair loose roof tiles and cracks in walls. For more information regarding this read the Advisory Notice - Strengthening of Existing Buildings on the Planning SA website. See also the Australian Standard 3826
  • Brace tall, free-standing bookshelves and water heaters to stop them falling over.
  • When furnishing your home keep chairs, lounges or beds clear of hanging items such as ceiling fans, hanging pictures or mirrors and hanging plants.
  • Store breakables and heavy items on bottom shelves.
  • Secure suspended cupboard doors with heavy latches.
  • Hazardous materials should be kept in waterproof containers and stored in a secure cupboard to prevent leakage.

What essentials you might need:

  • Keep a battery powered radio and torch by your bed.
  • Talk to your family about the safest areas for you to shelter during earthquakes (see 'During an earthquake'). Also decide on a place where you would meet in the event that you become separated.
  • Keep a list of emergency numbers readily available, such as police, State Emergency Service, fire, ambulance, and gas, power and water supplies.
  • Maintain a store of at least three days worth of emergency non-perishable foods and water supply.

Impact that an earthquake can cause

  • Shaking buildings and houses can cause objects and debris to fall resulting in human injury or casualties. The longer an earthquake lasts, the more extreme the damage.
  • Many deaths have occurred from people moving prematurely during an earthquake and being struck by falling objects.
  • Fallen power lines can leave communities without power.
  • Broken chimneys, gas or electrical lines can cause fires. Chemical spills create hazards, and broken water mains can cut water supplies.
  • Earthquakes can trigger landslides and seismic sea waves (tsunamis). If dams fail, flash flooding can occur.

During an Earthquake

  • DROP, COVER AND HOLD ON - If indoors, stay there (keep clear of falling debris outside). Shelter under (and hold onto) a sturdy table, bench or interior doorframe.
  • Keep clear of windows, chimneys and overhead fittings. In high-rise buildings, stay clear of windows and outer walls. Get under a desk.
  • Don't use lifts because you may be trapped.
  • In crowded areas or buildings, don't rush for the doors. Move clear of overhead fittings and shelves.
  • If outside, keep well clear of buildings, overhead structures, walls, bridges, power lines and trees.
  • In a city street, shelter from falling debris under strong archways or doorways of buildings. Don't stand under awnings or parapets because they may collapse.
  • In a vehicle, stop in an open area until the shaking stops. Beware of fallen power lines, damaged roads, including overpasses and bridges; and landslides.
  • Listen to your car radio before moving.

After an Earthquake

  • Watch for hazards and tend to injuries.
  • Turn off electricity and water. Don't light matches. Check for fuel leaks and damaged wiring.
  • Check for injuries. Apply first-aid. Don't move the seriously injured unless in immediate danger.
  • Check for broken water, sewerage or electrical mains.
  • Don't use the phone immediately (to avoid congestion) unless there is a serious injury or fire.
  • Check for cracks and damage in the roof, walls and chimneys.
  • Expect aftershocks, so evacuate if the building is damaged.
  • Listen to the local radio and heed warnings or advice on damage, service disruptions and evacuation.
  • Don't waste food or water because the supply may be interrupted.
  • Avoid driving unless for an emergency (keep the streets clear for emergency services).
  • Don't go sightseeing or enter damaged buildings.
  • Stay calm and help others if possible.
SES Earthquake 2
If you experience an earthquake, or know of an earthquake that occurred recently, Geoscience Australia would like you to fill in an online form to help them record the data. Please click here to visit their website.

Measuring an earthquake

Magnitude - Energy released by (or magnitude of) an earthquake is calculated from a recording device called a seismograph, using a magnitude scale. The best known magnitude scale was developed by Richter. The most severe earthquakes so far, have not exceeded magnitude 9.5 . If you would like further information on the magnitude scale visit http://www.ga.gov.au/urban/factsheets/earthquakes_measurement.jsp

Intensity - Another scale used to describe earthquakes is the modified mercalli (MM). It rates the amount of shaking felt at a particuar place and damage caused, (or intensity) and uses Roman numerals. On this scale, I = detectable by instruments only, XII = total destruction. For more information on the Mercalli scale visit the PIRSA website.

 


More information and associated Links

SA Government

Primary Industries & Resources SA

Emergency Management Australia

Geoscience Australia (formerly: Australian Geological Survey)

Seismology Research Centre, Melbourne

Australian Earthquake Engineering Society

University Of Queensland Advanced Centre for Earthquake Studies

National Earthquake Information Centre (US)

New Zealand Hazards

The Pacific Northwest Seismograph Network