Tsunami

A tsunami is a series of powerful ocean waves caused by sudden events like:

  • Earthquakes
  • Landslides
  • Volcanic eruptions
  • Meteorite impacts
  • The word tsunami comes from Japanese and means “harbour wave.” You might have heard them called tidal waves or seismic sea waves, but those names can be confusing. Tsunamis aren’t caused by tides or only by earthquakes—they can come from many types of natural events.

Tsunamis are also different from storm surges, which are caused by weather events like cyclones.

DO TSUNAMIS AFFECT AUSTRALIA AND REACH LAND?

Yes, they can. Australia is near active tectonic plate boundaries that can cause tsunamis. These waves could reach our shores within 2 to 4 hours after an event.

  • On average, a tsunami is recorded in Australia every two years. Most are small and don’t flood land, but they can still be dangerous for:
  • Swimmers
  • Boaters
  • People near the shore

Even small tsunamis can create strong currents and dangerous waves.

As a tsunami moves from deep ocean to shallow water, it slows down—but the wave gets taller. This is why a tsunami might be barely noticeable at sea but grow several meters high near the coast.

When it hits land, it can:

  • Erode beaches
  • Uproot trees
  • Damage buildings
  • Flood areas far inland

Some tsunamis can reach heights of tens of meters above sea level.

TSUNAMI WARNINGS

Australia’s Joint Tsunami Warning Centre (JATWC) monitors for tsunami threats and issues alerts in two stages:

Stage 1: Tsunami Watch

  • An undersea earthquake is detected.
  • A Tsunami Watch is issued if there’s a possible threat.

If no threat is found, a No Threat Bulletin is sent.

Stage 2: Tsunami Warning

  • A warning is issued if a tsunami is confirmed or could hit within 90 minutes.
  • Warnings are specific to each state or territory.

Types of Tsunami Warnings

  1. No Threat
    • No tsunami danger.
    • No action needed.
  2. Marine & Foreshore Threat
    • Dangerous waves and currents near the shore.
    • 儭 Stay out of the water and away from the beach.
  3. Land Inundation Threat
    • Flooding possible in low-lying coastal areas.
    • Move at least 1 km inland or to higher ground (10 m above sea level).

When Is It Safe Again?
The Bureau of Meteorology (BOM) will cancel warnings when the threat is over. Local emergency services will let you know when it’s safe to return.

STAYING INFORMED

You can get tsunami warnings from:

  • Audio warning service: 1300 878 626
  • News and media
  • Local emergency services

Warnings are also sent to:

  • Emergency services
  • Councils
  • Port authorities
  • Police

More Information