Earthquakes

Discover related resources in the  Understanding Hazards Collection and on the Big Weather page.

World map showing the major tectonic plates, with each plate labelled and shaded in different colours. Visible plates include the Pacific, North American, South American, African, Eurasian, Australian, Antarctic, Indian, Arabian, and smaller plates such as the Nazca, Caribbean, Philippine, Cocos, and Juan de Fuca plates, with boundaries marked between them.

The boundaries and current locations of the Earth’s tectonic plates. Source: United States Geological Survey

The Earth’s crust rests on top of a hot, slowly flowing layer of partly melted rock in the Earth’s mantle. This causes the tectonic plates in the crust to move over time.

 

Diagram of Earth’s internal structure showing a cross-section from the crust to the core. The thin outer crust sits above the mantle and asthenosphere, followed by the liquid outer core and solid inner core, with depth measurements labeled and notes indicating temperature increases and changes in material from rock to liquid and solid.

The Earth is made up of layers of rock which surround the core. Source: United States Geological Survey 

 

When tectonic plates move against each other, friction can cause the plates to get stuck, and pressure can slowly build up between them over time. Earthquakes happen when this pressure is suddenly released and the rocks suddenly break or slip along cracks called faults. This energy travels from the epicentre as seismic waves through the crust, causing it to vibrate and shake – what we feel as an earthquake.

The size and intensity of earthquakes are measured using seismometers which record seismic waves. The size of the earthquake is indicated by its magnitude (using the Richter scale). A smaller number (2 or 3) means a small earthquake that people may not feel. A bigger number (6 or 7) means a strong earthquake that can cause damage.

The highest magnitude earthquake ever recorded globally was the Valdivia earthquake in Chile in 1960, with a magnitude of 9.5.

 

Earthquakes can occur anywhere on the Earth’s surface. However, they are more frequent and severe along tectonic plate boundaries. The Pacific Ring of Fire is a belt of tectonic plate boundaries that surround the Pacific Ocean. 90% of the world’s earthquakes occur along this belt, and it contains 75% of all active volcanoes on Earth.  

Countries like Japan, New Zealand and Indonesia experience more frequent earthquakes as they lie close to the boundary of multiple tectonic plates on the Ring of Fire.

A labelled world map highlighting the “Ring of Fire,” a horseshoe-shaped zone around the Pacific Ocean marked in red. The shaded region follows the western coasts of North and South America, across Alaska and the Aleutian Islands, down through East and Southeast Asia (including Japan, the Philippines, and Indonesia), and into the southwest Pacific near New Zealand. Major ocean trenches are labelled along this boundary, including the Aleutian, Kurile, Japan, Izu Bonin, Mariana, Philippine, Ryukyu, Java (Sunda), Bougainville, Tonga, Kermadec, Middle America, Peru-Chile, Puerto Rico, and South Sandwich trenches. A red dot marks “Challenger Deep” in the western Pacific near the Mariana Trench. The equator is shown crossing the Pacific Ocean. The continents are beige, oceans are light blue, and trench lines are drawn in darker blue.

The Pacific Ring of Fire. Source: United States Geological Survey

You can find more information about some of Australia’s largest earthquakes via the interactive Disaster Mapper.

impacts

Earthquake safety infographic showing ‘Drop, Cover, Hold On’ steps. Includes instructions for people without aids (‘drop, cover under sturdy furniture, hold on’), and adaptations for people using a cane, walker, or wheelchair (‘drop or lock, then cover and hold on’).

Earthquake protective action graphics for people with mobility disabilities. Source: Earthquake Country Alliance

Prepare, plan and stay safe

Governments have information about how to stay safe in an earthquake, including dealing with aftershocks.

Northern Territory

Queensland

South Australia

Victoria

Western Australia

Australian Capital Territory

Tasmania