Response: What to do during a tsunami

For a local-source tsunami which can arrive in minutes, there is not enough time for an official warning. It is important to recognise the natural warning signs and act quickly.

Remember, LONG or STRONG, GET GONE.

If there is earthquake shaking, drop, cover and hold. Protect yourself from the earthquake first, then act as soon as the shaking stops.

If you are near the coast, you need to act immediately if you experience any of the following:

• Feel a strong earthquake that makes it hard to stand up, or a weak rolling earthquake that lasts a minute or more.
• See a sudden rise or fall in water level.
• Hear loud and unusual noises from the water.

Move immediately to the nearest high ground or as far inland as you can, out of tsunami evacuation zones. Do not wait for official warnings.

Walk, run or cycle, if you can. This reduces the chances of getting stuck due to damaged roads or traffic congestion.

While evacuating, be aware of other hazards. For example, a large local earthquake may damage powerlines and bridges and create liquefaction and landslides.

Do not return until an official all-clear message is given by Civil Defence Emergency Management. Tsunami activity can continue for several hours, and the first wave may not be the largest. If there was an earthquake, expect aftershocks. Each time you feel one, drop, cover, and hold. Aftershocks may generate another tsunami.

Listen to the radio and/or TV for updates, local CDEM Groups’ websites and social media and @NZCivilDefence Twitter.

When tsunami travel across the ocean from far away, there is time to issue official warnings.

The National Emergency Management Agency is responsible for issuing tsunami warnings in New Zealand.

Tsunami warnings are published on www.civildefence.govt.nz and Twitter @NZCivilDefence. Tsunami warnings will also be broadcast on radio and television.

If there is a land threat, Emergency Mobile Alerts (EMA) will be issued by the National Emergency Management Agency and Civil Defence Emergency Management Groups to areas under threat.

If strong and unusual currents and unpredictable surges are expected near the shore, a local EMA may be issued by your local Civil Defence Emergency Management Group.

Your local area may have its own methods for broadcasting warnings. These might include sirens, phone calls, local EMAs, or warnings through loud hailers. Contact your local Civil Defence Emergency Management Group or your local council to find out about the warnings you can expect to receive in your area.

Immediately follow the advice of any emergency warning. Do not wait for more messages before you act.

Depending on the location of the earthquake, you may have a number of hours in which to take appropriate action.

Tsunami threat to land and marine areas warning

A tsunami threat to land and marine areas warning will be issued when coastal inundation (flooding of land areas) is expected, and unusually strong and hazardous currents and unpredictable surges are expected near the shore.

• The land warning may apply to all of New Zealand’s coastline, or only to certain areas.
• A land warning means that evacuations may be required in some areas.
• An Emergency Mobile Alert will be issued to the areas under land threat. This will advise people to evacuate immediately or prepare to evacuate.
• Listen to local Civil Defence Emergency Management authorities and follow any instructions regarding evacuation of your area.

Tsunami activity advisory

A tsunami activity advisory will be issued when inundation of land areas near the shore is not expected (although this assessment may change), but strong and unusual currents and unpredictable surges are expected near the shore.

• The tsunami activity advisory may apply to all of New Zealand’s coastline or only certain areas.
• Strong currents and surges can injure and drown people. There is a danger to swimmers, surfers, people fishing, small boats and anyone in or near the water close to shore.
• People on boats, liveaboards and at marinas should leave their boats/vessels and move onto shore. Do not return to boats unless instructed by Civil Defence.
• Evacuation of land areas is not required but people should stay out of the water (sea, rivers, and estuaries, including boats) and stay off beaches and shore areas when a tsunami activity advisory is issued.
• Do not go swimming, surfing, fishing or engage in small boat activities when a tsunami activity advisory is issued.

A tsunami warning could also come from friends, neighbours, your community or international media. If you trust them and you feel unsafe, consider evacuating.

If you feel a tsunami threat is imminent, move immediately to the nearest high ground or as far inland as you can, out of tsunami evacuation zones.

Check the accuracy of the warning once you have arrived at your safe location or en route only if it won’t slow you down. You can check the warnings at civildefence.govt.nz or via TV/radio broadcasts, news websites, or through your local Civil Defence Emergency Management Group and emergency services.

If official warnings are available, trust their message over informal warnings.

Anyone near the coast who feels a long or strong earthquake should self-evacuate as soon as the shaking stops. Do not wait for an official warning.

If you are inside a tsunami evacuation zone when a tsunami is expected, you may need to evacuate.

If you are outside of tsunami evacuation zones you do not need to evacuate. If you stay where you are, it will help to reduce congestion for those who must evacuate.

Advised to evacuate immediately

Land and marine tsunami warnings for local and regional tsunami will advise people near the coast in affected areas to evacuate immediately.

The National Emergency Management Agency will issue an Emergency Mobile Alert to areas under land threat advising people near the coast in affected areas to evacuate immediately. Civil Defence Emergency Management Groups will also issue supporting Emergency Mobile Alerts providing local information.

• Do not wait for an Emergency Mobile Alert if you felt a long or strong earthquake. Self-evacuate as soon as the shaking stops. Remember, LONG or STRONG, GET GONE.

If you are advised to evacuate immediately, you should:

• Move immediately to the nearest high ground or as far inland as you can, out of tsunami evacuation zones.
• Walk, run or cycle, if you can. This reduces the chances of getting stuck due to damaged roads or traffic congestion, especially in a local source tsunami event where there may only be a few minutes available to get to safety. Use of vehicles on roads should be limited to emergency services and those with mobility impairments, including wheelchair users.
• If you have to drive, keep going once you are well outside of all evacuation zones, to allow room for others behind you.
• Evacuate via the routes shown on tsunami evacuation route signs or drawn on tsunami evacuation maps if these are available.
• Take your grab bag with you if possible, but do not travel into the evacuation zone to collect your grab bag or other belongings.
• Take your animals with you only if it will not delay you. Do not spend time looking for them and if you are not at home, do not return to get them.

Advised to prepare to evacuate

Land and marine tsunami warnings for distant tsunami will advise people near the coast to prepare to evacuate. If you are advised to prepare to evacuate you should:

• Listen to local Civil Defence Emergency Management authorities and follow any instructions regarding evacuation of your area.
• Leave cell phones on and charged so you can receive alerts.
• Listen to the radio or TV for updates, and check your local Civil Defence Emergency Management Group’s website
• Find any pets and bring them with you when you evacuate, only if it will not delay you.
• Put essential items such as food, clothing, and medication in your grab bag to take when you evacuate.
• Secure your whare/home as you normally would when leaving for an extended period.
• Share information with your neighbours. They may not be aware of the tsunami warning. Help neighbours who need assistance to evacuate.
• If you are farming along the coast or river estuary, evacuate your whānau/family and staff first. If you have time, move livestock to higher ground.

When it is time to evacuate:

• Evacuate via the routes shown on tsunami evacuation route signs or drawn on evacuation maps if these are available. If these routes appear slow or congested, use a different route.
• Walk, run or cycle, if you can. This reduces the chances of getting stuck due to damaged roads or traffic congestion.
• If you have to drive, keep going once you are well outside of all evacuation zones, to allow room for others behind you.

Cancellations

Once you have evacuated, follow official advice from your local Civil Defence Emergency Management Group about when it is safe to return to tsunami evacuation zones. Do not return until an official all-clear message is given by Civil Defence Emergency Management. Tsunami activity will continue for several hours and the first wave may not be the largest. Aftershocks may cause additional tsunami events.

Tsunami are often most destructive in bays and harbours, not just because of the waves, but because of the strong currents they generate in local waterways. Tsunami dangers for boats include:

• Strong and unpredictable currents and surges that can affect ports and marinas even during small tsunami.
• Grounding of vessels, as water levels can suddenly drop.
• Capsizing from incoming surges (bores), complex coastal waves, and surges hitting grounded boats.
• Collision with other boats, docks, debris and changes to the seafloor (e.g. movement of sand bars, wrecks, reefs and boulders).

Depending on the nature of the tsunami and your location, you may need different action plans:

• What would you do if you were getting ready to head out? Out on the water? Coming back in?
• What would you do if you had minutes until a tsunami hit – or an hour, or a few hours?

Always have at least three days, or a week or more if you can, of food, fuel, and water.

In the event of a potential tsunami threat, Coastal Navigational Warnings will be issued by the Rescue Coordination Centre New Zealand (RCCNZ), via Maritime Radio. Along with the RCCNZ, the National Emergency Management Agency will advise each regional Civil Defence Emergency Management Group (CDEM Group). Each regional CDEM Group will inform the mariner as quickly as possible via their regional council and harbourmasters/port authorities. Port authorities would likely take their own precautions as per their Emergency Operating Procedures.

For further information check out these helpful resources:

• https://www.hbemergency.govt.nz/assets/Uploads/Tsunami-Boat-Safe-Distance1.png
• https://www.linz.govt.nz/sea/nautical-information/new-zealand-nautical-almanac-nz-204/download-new-zealand-nautical-almanac-nz-204

Local source tsunami

In a local source tsunami, which can arrive in minutes, you need to take action quickly. Be aware of the natural warning signs:

• Onshore:
  • Feel a strong earthquake that makes it hard to stand up, or a weak rolling earthquake that lasts a minute or more.
  • See a sudden rise or fall in water level.
  • Hear loud and unusual noises from the water.
• Offshore:
  • You may feel the earthquake through the hull of your boat.
  • You could see a rapid and extreme shift in currents and simultaneous changes in wind wave heights.

If you are on land or tied up at dock, and you see or hear natural warning signs of a tsunami, leave your boat, move immediately to the nearest high ground or as far inland as you can, out of tsunami evacuation zones.

If you are on the water shallower than 50 metres or 27.3 fathoms depth:

• Stop commercial fishing operations immediately.
• Free the vessel from any bottom attachment and gear that might drag in currents (cut lines if necessary).
• If you can beach or dock your small boat and evacuate on foot within ten minutes of a natural warning, then this is your best chance.
• If evacuation on foot is not possible, head for the deepest water possible, greater than 50 metres deep.
  • Proceed directly away from the shore.
  • Sail directly into waves. Be aware that tsunami can interact with wind waves and produce unusual effects.

Maintain as much separation as possible from other vessels. If you are on the water at greater than 50 metres outside of harbours/channels, continue to head to deeper water which is safer from tsunami currents and waves.

• Do not return to port if you are at sea and a tsunami warning is issued. Port and harbour facilities may become damaged and hazardous with debris.
• Listen to maritime radio reports to find out when it is safe to return and be careful navigating when you return as the seafloor may have changed and there may be debris.

Regional or distant source tsunami

Check with your local harbourmaster to find out what your local tsunami response procedures are.

Follow official advice from your local Civil Defence Emergency Management Group about when it is safe to return to tsunami evacuation zones. Do not return until an official all-clear message is given by Civil Defence Emergency Management. Tsunami activity will continue for several hours and the first wave may not be the largest.

• If there was an earthquake, expect aftershocks. Each time you feel one, drop, cover, and hold. Aftershocks may generate another tsunami. Be prepared to evacuate.
• Be cautious in and around coastal water, tidal estuaries, rivers and streams after any tsunami or tsunami warning, as even small waves create dangerous currents that can injure or drown people.

Tsunami can happen at inland locations in lakes and other large bodies of water – not only on the coast.

Lake tsunami can be caused by earthquakes, landslides (starting above the lake or underwater), rock falls, volcanic eruptions, dam failures and glacier collapses.

Even a small earthquake could trigger a large landslide at a mountain lake or fiord/sound that generates a tsunami. In these cases, natural warning signs may be weak or unnoticeable.

It is important to recognise natural warning signs and act quickly.

If you are at a lake or any other large body of water, move away from the water's edge to higher ground immediately if you experience any of the following:

• Feel a strong earthquake that makes it hard to stand up, or a long weak rolling earthquake that lasts a minute or more. Remember: LONG or STRONG, GET GONE.
• See a sudden rise or fall in water level, or unusual waves or water behaviour without an obvious cause (such as the wind or a boat).
• See indications of landslides or rock falls occurring (for example, rocks falling or large dust clouds).
• Hear loud and unusual noises from the water or surrounding area (for example, glacier cracking or rocks falling).

More information about lake tsunami is available on the GeoNet website.