Where do Tsunamis occur?

Tsunami origins

Tsunami origins

There is evidence that the Australian coast may have experienced large tsunami during the past few thousand years. This evidence is revealed through deposits of shell, coral and boulders which are well above sea level and several kilometres inland. Tsunami are recorded in Australia about once every two years but most are small and present little threat to coastal communities.

The tsunami hazard faced by Australia ranges from relatively low along the southern coasts of Australia to moderate along the north west coast of Western Australia. This area is more susceptible because of its proximity to Indonesia and other countries in the region which are prone to significant earthquake and volcanic activity.

Several significant tsunami have hit Australia's north west coast with the largest, at Cape Leveque in 1977, reportedly producing a six metre wave height.

Interesting fact: A tsunami reached the Australian coast at Steep Point on 17 July 2006 generated by a magnitude 7.7 earthquake south of Java. The tsunami caused widespread erosion of roads and sand dunes, extensive vegetation damage and destroyed several campsites up to 200 metres inland. The tsunami also transported a 4WD vehicle ten metres. Fish, starfish, corals and sea urchins were deposited on roads and sand dunes well above the regular high-tide mark.

Further north in the Onslow-Exmouth region in June 1994, tsunami waves travelled inland to a point four metres above sea level and washed 300 metres inland after appearing out of a calm sea. Both tsunami were generated by earthquakes in Indonesia.

In May 1960, a magnitude 9.5 earthquake in Chile generated the largest tsunami recorded along the east coast of Australia. The event generated tsunami waves of just under one metre at the Fort Denison tide gauge in Sydney Harbour. Slight to moderate damage was caused to boats in harbours at Lord Howe Island, Evans Head, Newcastle, Sydney and Eden.