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TSUNAMIS
TIDAL WAVES
Tsunamis begin as long low waves caused
by earthquakes or landslides on
the continental shelf. They are scarcely visible
in the open ocean, but on shallow coasts
they become heaped up into great waves
and can cause devastation.
| Recordings of small tsunamis on the Central Coast | |
|---|---|
| 16 May 1995 | Wave heights of 0.6 metres (2 feet) on tide charts in Sydney Harbour caused by an earthquake in the Loyalty Islands. |
| 1868, 1877, 1960 | Tsunamis of 0.5 metres caused by earthquakes in Chile when the tide went up and down every 30 minutes. |
There is evidence that more destructive larger tsunami waves,
up to 15 metres high and driving inland about 10 kilometres
have swept the east coast of Australia
five times in the last 5000 years.
Greater tsunamis along our coast could be triggered by meteorites
or comet impacts in the Southern Ocean.
Such an event could be about once in 50 million years.