Travel time (in hours) to Australia for tsunami
waves generated from undersea earthquakes close
to Australia (source: see 'Tsunami Speed' below). Source: National Tsunami Community Education Strategy licensed under Creative Commons BY 3.0.
Tsunami is a Japanese word meaning harbour wave. A tsunami is a series of ocean waves caused by large disturbances of the ocean and travel at speeds up to 900 km/h in deep water. The first wave in the series may not necessarily be the largest. A tsunami is different from a wind generated surface wave on the ocean as a tsunami involves the movement of water from the surface to the seafloor. In shallow water tsunamis increase in height, up to 30 meters above sea level in some cases.
Tsunamis usually result from earthquakes on the sea floor, landslides, volcanic eruptions, meteorological events or meteorite impacts.
Around Australia tsunamis are recorded about once every two years but are usually small and present a low threat to coastal communities. In Western Australia, tsunami are more likely along the north west coast due to the proximity to Indonesia and other countries with high seismic and volcanic activity.
In Australia, tsunami warnings are provided by the Joint Australian Tsunami Warning Centre (JATWC) operated by The Bureau of Meteorology and Geoscience Australia. The Centre continually monitors, detects, verifies and warns the Australian community of potential tsunami threats.
Tsunamis can threaten both the marine and land environments.
The tide level at the time of tsunami arrival will influence the amount and severity of impacts to coastal communities. For a given tsunami wave height, the impact will be lessened at low tide compared to high tide due to the combined height of the tide and tsunami height. In areas with large tidal ranges, such as the Kimberley where the difference between low and high tides is as much as 14m, the influence of tides will be more pronounced.
The number one warning sign of a tsunami in Australia is the advice you may receive from the media (on radio or television) or from police and other emergency services. Natural warning signs of a tsunami, such as ground shaking in coastal regions, withdraw of water from the shoreline or roaring sounds, may be, but not always, experienced prior to a tsunami. If you notice any of these natural warning signs take action.
Early detection and warning of a potential tsunami, evacuation of potential impact areas, physical controls such as sea walls and community risk awareness are important controls.
More information about Tsunami can be found at: