A tsunami is a series of ocean waves with very long wavelengths (typically hundreds of kilometres long), caused by large disturbances of the ocean floor. These disturbances are most commonly undersea earthquakes, but could also be landslides, volcanic eruptions, explosions or meteorite impacts. They have the potential to cause disastrous inundating waves, however Australia usually experiences their effects only as dangerous rip currents and unusual tidal variations. These variables are reflected in the tsunami warning levels issued by the Joint Australian Tsunami Warning Centre. [13]
- No threat—an undersea earthquake has been detected; however, it has not generated a tsunami, or the tsunami poses no threat to Australia and its offshore territories.
- Marine and immediate foreshore threat—warning of potentially dangerous rip currents, waves and strong ocean currents in the marine environment and the possibility of only some localised overflow onto the immediate foreshore.
- Land inundation threat—warning for low-lying coastal areas of major land inundation, flooding, dangerous rip currents, waves and strong ocean currents.
Refer to the Australian Institute for Disaster Resilience for more information about planning for tsunamis.