Tsunami are recorded in Australia about once every two years, and most are small and present little threat of land inundation to our coastal communities. However the abnormal waves, tides and currents caused by even relatively small tsunami can be dangerous to swimmers and mariners.
As a result of the Australian Tsunami Warning System (ATWS) Project, jointly undertaken by the Bureau of Meteorology (Bureau), Geoscience Australia (GA) and Emergency Management Australia (EMA) and funded by the Australian Government, Australia now has a comprehensive, independent tsunami warning service to advise the media, public and emergency authorities of any tsunami threat to Australia and its offshore territories.Tsunami Watches and Warnings for Australia
The Joint Australian Tsunami Warning Centre (JATWC), jointly operated 24 hours a day by the Bureau and GA detects, monitors, verifies and warns of any tsunami threat to the coastline of Australia and its offshore territories.
The first stage of the tsunami warning process is a 'tsunami watch' phase, where seismologists have determined that there is the potential for an identified undersea earthquake to cause a tsunami threat to Australia. If there is a threat, the Bureau would issue a National Tsunami Watch. If there is no threat, a National Tsunami No Threat Bulletin would be issued.
The National Tsunami Watch may be reissued if a tsunami remains unconfirmed by sea level observations and any potential first point of impact on Australia is more than 90 minutes away (the minimum time criteria for warning).
The National Tsunami Watch may be reissued if a tsunami remains unconfirmed by sea level observations and any potential first point of impact on Australia is more than 90 minutes away (the minimum time criteria for warning).
If sea level observations and further data confirm the tsunami threat, or if any potential first point of impact is less than 90 minutes away, the Bureau, on behalf of the JATWC, will use its severe weather communication infrastructure to issue Tsunami Warnings for the States and Territories under threat. The Bureau's Regional Forecasting Centres (RFCs) in capital cities are the main liaison point for emergency services during tsunami events.
Once separate tsunami watches or warnings are being issued for individual States and Territories, a National Tsunami Warning Summary will also be issued listing all the watches, warnings and cancellations that are in effect for the current tsunami event. The JATWC website www.bom.gov.au will provide a complementary coastal threat graphic showing the regions currently under threat.
Cancellation of a Tsunami Warning
When the main threat has passed or if a tsunami didn't eventuate, the Bureau will issue a Tsunami Watch Cancellation or Tsunami Warning Cancellation. The relevant State or Territory emergency authority will inform the public when it is safe to return to the affected area. A National Tsunami Event Summary is then issued after the event.
Distribution of Tsunami Bulletins and Warnings to the Media and Public
Tsunami Bulletins, Watches, Warnings, Cancellations and Event Summaries are part of a suite of warnings for severe weather events and hazards issued by the Bureau of Meteorology.
Media organisations across Australia work with the Bureau to also inform the public in the case of a tsunami event. Tsunami Warning distribution lists are maintained at each of the Bureau's State and Territory RFCs. These distribution lists are used for both National JATWC Bulletins and Regional Warnings. In addition to the media, key agencies such as the State and Territory emergency services, local councils, port authorities, and police are included on these dissemination lists. The bulletin and warning messages are also automatically uploaded to the Bureau's website.
Tsunami Warning Messages Summary
Messages: Types and Purpose
- National No Threat Bulletin:
- To advise people that the earthquake has been assessed and that no tsunami threat exists
- National or State/Territory Watch:
- To advise people that a tsunami threat may exist and that they should look out for further updates
- State/Territory Warning:
- To advise people that a tsunami threat does exist and to advise them of the level of threat and action they should take marine = blue, land = red
- National Warning Summary:
- To provide the public, media and emergency authorities with the status of tsunami warnings nationally
- Event Summary:
- To provide the public, media, emergency authorities and government with summary information that can be used in post-event analysis
Messages: Layout & ContentMessages
- Product Identifier:
- Identify type product/auto notifier
- Media Instructions:
- How urgently message/s should be broadcast. Use of Standard Emergency Warning Signal (SEWS) or not
- Message Title and Issue:
- Time Type, date/time and number sequence of message
- Headline Message:
- Key message; eg. No Threat, Potential Threat, Threat
- Summary:
- What, where and when the threat is
- Threat Information:
- Level of threat , coastal areas affected, time of Arrival
- Community Response Advice:
- What action people should take
- Next Update Time:
- When the next update will be issued:
- Where the Public can get Further Information:
- Web and telephone details for further/latest information
Tsunami watches and warnings indicating the level of threat are issued for coastal zones around Australia and its offshore territories.Categories of Threat Levels within Tsunami Warnings
In order to assist the community, tsunami threat levels in Regional Tsunami warnings are categorised into three levels with required community responses; these have been determined in consultation with emergency management authorities. These Threat Levels will be specified for the same coastal areas that are used for routine Bureau Coastal Waters Forecasts, already known to marine users.
- 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 waves, strong ocean currents in the marine environment and the possibility of only some localised overflow onto the immediate foreshore.
- Land inundation threatWarning for low-lying coastal areas of major land inundation, flooding, dangerous waves and strong ocean currents.
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