Tsunami

The SES is the designated combat agency for tsunami. Following is information on what a tsunami is, the different warnings issued for a tsunami in NSW and how you can be prepared should one occur.

An important role of the SES is to respond to the flooding and damage caused by tsunami. 

A tsunami is a series of waves generated by one of four causes:

• Vertical movement of the sea floor as the result of a large earthquake
• Submarine or coastal volcanic eruptions
• Meteor impacts
• Coastal landslides and slumps, either land-based or submarine

The NSW coast has been affected by over 30 tsunami in the past 200 years but these have been generally too small to be noticed. The largest tsunami to have affected the NSW coast in recent times occurred in May 1960 after a 9.5 magnitude earthquake in Chile resulted in a 1 metre tidal fluctuation at Fort Denison in Sydney Harbour. This caused some damage to boats and coastal infrastructure.

The following quote provides some indication of the damage caused by the 1960 tsunami in Sydney:

"Freak currents tore away moored boats and upset shipping. The huge tide tore from their moorings about 30 launches and small craft and two barges at the spit: swirled the barges in among drifting launches, overturning several of them and damaging others: smashed one of the barges into the spit bridge. Set adrift 800 logs from moorings at Balmain shipping yard, which were then swept down the Parramatta River. Swept away a strip 100 yards by 60 yards from Clontarf Reserve Point Park exposing a high tension submarine cable: in one tense moment a 30ft. fishing trawler sank in Throsby Creek near Newcastle. Eight launches were ripped from their moorings in  Throsby Creek and swept half a mile into Newcastle Harbour." (Brisbane Courier Mail, 25 May 1960)

The SES has worked closely with other State and Federal Government agencies in the development of a NSW Tsunami Sub Plan . This sets out the responsibilities of the SES and other agencies in warning of and managing the effects of a tsunami.

The SES is ideally placed to provide assistance along with other emergency services. Should a tsunami occur, the SES would coordinate the warning and evacuation of at-risk areas prior to its arrival. After a tsunami has impacted the coast, the SES would be active in such tasks as reconnaissance of areas likely to have been impacted, making temporary repairs to damaged buildings, rescuing people trapped by flooding caused by the tsunami and providing isolated communities with supplies. It is important to remember not to enter or re-enter a location impacted by tsunami until the all clear has been given by the NSW SES.

Based on the risk posed by tsunami, the Bureau of Meteorology will issue:

• Tsunami Watch. Advises people that a tsunami threat may exist and that they should look out for further updates
• Tsunami Warning. Advises people that a tsunami threat does exist and to advise them of the level of threat and action they should take

Tsunami watches and warnings are issued with three types of Threat Levels:

1. No Threat . Advises that the tsunami has been assessed and that no tsunami threat exists
2. Marine and Immediate Foreshore Threat. A warning with a marine and immediate foreshore threat level warns coastal communities including swimmers, fishermen, beach users and boaters of potentially dangerous waves, strong ocean currents and the possibility of overflow onto the immediate foreshore. Tsunami warnings with a marine and immediate foreshore threat level are more common than those with a land inundation threat
3. Land Inundation Threat. A Tsunami Warning with a land inundation threat level warns low-lying coastal areas of major land inundation, flooding, dangerous waves and strong ocean currents. Warnings with a land inundation threat are low frequency but have the potential to cause widespread damage and place lives at risk  

It is important to act early on warnings advice as Australia lies adjacent to an active plate boundary capable of generating tsunami, which could reach our coastline within two to four hours.

Actions to take

Now and always

Be aware of your risks, do you live in a low lying coastal area close to the beach, an estuary, a river or any other coastal inlet.

Find out what local radio station you should listen to if there is ever an emergency situation in your local community or the communities you visit during the holiday period.

You may be in an area where an official warning will not be available, therefore you should be aware of the natural warning signs that a tsunami is approaching.

• You may see the ocean drop. As tsunami approach the shoreline, the sea level may, but not always recede or drop dramatically before returning as a fast moving series of waves.
• You may hear an unusual roaring sound from the ocean before the arrival of a tsunami.

When a tsunami watch is issued

People in affected areas:

• Locate your emergency kit and add any medications, important papers, special items for babies, elderly, clothing, food and water
• Locate your emergency plan
• Keep listening to your local radio station for updates and advice

Actions to take when a Tsunami Warning is issued

It is important to act early on warnings advice as tsunamis can reach the coastline within two to four hours.

Follow the advice of the emergency services.

Marine and Immediate Foreshore Threats

• Get out of the water and move away from the immediate water's edge of harbours, coastal estuaries, rock platforms, and beaches
• Boats in harbours, estuaries and in shallow coastal water should return to shore. Secure your boat and move away from the waterfront
• Vessels already at sea should stay offshore in deep water until further advised
• do not go to the coast to watch the tsunami
• Check that your neighbours have received this advice
• Keep listening to your local radio station for updates and advice

A Tsunami Warning Cancellation will be issued when the tsunami threat has passed

Land Inundation Threat

• Go to higher ground, at least ten metres above sea level, or if possible move at least one kilometre away from all beaches and the water's edge of harbours and coastal estuaries
• Take only essential items that you can carry including important papers, family photographs and medical needs
• Consider walking to safety if possible to avoid traffic jams
• If you cannot leave the area take shelter in the upper storey of a sturdy brick or concrete multi-storey building
• Get out of the water and move away from the immediate water's edge of harbours, coastal estuaries, rock platforms and beaches
• Boats in harbours, estuaries and in shallow coastal water should return to shore. Secure your boat and move away from the waterfront
• Vessels already at sea should stay offshore in deep water until further advised
• Do not go to the coast to watch the tsunami
• Check that your neighbours have received this advice
• Keep listening to your local radio station for updates and advice

A Tsunami Warning Cancellation will be issued when the tsunami threat has passed

After a tsunami event

Do not return to the threat area until the all clear has been given by the emergency services.

Tsunami can occur as a sequence of waves, it is important to check with authorities if it is all clear before returning to the treat area.

Tsunami Awareness Information Brochures are available from Emergency Management Australia.

Tsunami Information in Different Languages page.