Tsunami

It is hard to imagine living in Western Australia (WA) that a tsunami could ever impact you and your family and potentially threaten your life.

A tsunami is a series of waves that can travel very fast, across the ocean due to the sudden movement of a large body of water. They are caused by undersea earthquakes, landslides on the sea floor, volcanic eruptions and even asteroid impacts.

While the threat in WA may be less than those experienced in neighbouring countries, our coastline remains particularly vulnerable as we are close to the Java Trench, a very active earthquake area.

The impact of a tsunami may be limited to foreshore areas and local waters as a marine threat or may extend beyond the foreshore and become a land threat.

A tsunami in WA is more likely to cause dangerous rips and currents and travel up river systems and estuaries rather than flood low lying land.

These dangerous rips and currents can last for more than 24 hours and beaches and marinas may be closed for several days.

If you receive an official tsunami warning visit DFES's Alerts and Warnings page, listen to your local radio and television announcements and follow the advice of emergency services.

What is a tsunami?

*A tsunami is different from regular ocean waves in several ways:

• A tsunami is a series of sea waves that are extremely long. As they cross the deep parts of the ocean the length from crest to crest may be as much as 150 kilometres and travel at speeds of 1,000 kilometres per hour
• As the tsunami moves to shallower water near the coast, the tsunami slows down and the wave height increases
• At sea a tsunami can be unnoticeable as it may only be a few centimetres high
• Regular ocean waves move in the top 150 metres of water, but a tsunami moves the water all the way to the sea floor. This means the water moved by a tsunami is significantly more than the amount moved by regular ocean waves
• As many tsunami are a series of waves, the first wave may not be the largest
• Depending on whether the first part of a tsunami to reach the shore is a crest or trough, it may appear as a rapidly rising or falling tide
• Even a small tsunami can be very dangerous to swimmers and mariners as it causes dangerous rips and currents
  
  *The above content has been provided by Emergency Management Queensland, the State Government of Queensland.

Additional Coverage

• Local tsunami research leads the world (FESA 24seven Magazine. Issue 2, 2011)