Australia is surrounded to the north and east by some 8000 kilometres of active tectonic plate boundaries capable of generating tsunami that would reach Australia within two to four hours. Furthermore, 50% of Australians live within 7 km of the shoreline, meaning that a considerable proportion of Australians are exposed to tsunami hazard.
Australia has never experienced a catastrophic disaster on the scale of the Indian Ocean tsunami of 2004. However, tsunami have impacted Australia during historical and prehistorical times, showing that a real tsunami threat exists.
The impact of a tsunami can vary widely. A small tsunami may result in unusual tides or currents that can be dangerous to swimmers or cause damage to boats and marinas. A large tsunami can cause widespread flooding and destruction, such as that seen off the west coast of Northern Sumatra on 26 December 2004. Large tsunami can cause strong rips and currents in oceans around the world for up to a few days after the initial earthquake.