A tsunami is a series of fast, low and long ocean waves that move out from a central area, due to a sudden disturbance of a large body of water.
In the deep ocean a tsunami can travel up to 950km/hr (the speed of an aeroplane) and may be less than one metre high.
As a tsunami approaches the coastline they slow down but do not lose energy. The back of the wave catches up with the front, causing the wave to grow in height - up to several metres. It is not so much this movement of water but the energy moving through it that makes tsunami so dangerous.
Historically, tsunamis are rare along the NT coastline. The NT has a low to moderate risk from tsunami because it is protected by shallow waters and a large tidal variation.
The Joint Australian Tsunami Warning Centre (JATWC) runs 24 hours a day to identify any tsunami threat to Australia. They use sea surface buoys and undersea sensors to measure earthquake activity and the likelihood of a tsunami affecting Australia.
In Australia, warnings will be issued through the media, but you should also listen to emergency workers, lifeguards and Surf Lifesavers.
If you hear a tsunami warning
- Move inland or to higher ground.
- Do not stay and watch.
- Do not go back to the beach until you are told it is safe.