Gone are the days long and strong earthquakes were used to warn of a tsunami and Bay of Plenty residents are being urged to take notes on the four warnings.

Emergency Management Bay of Plenty is reminding residents visiting or living in coastal areas of the warning signs for a potential tsunami.

People need to self-evacuate if any of the triggers are felt:

• feel a long or strong earthquake
• hear a loud roar coming from the ocean
• see the ocean suddenly rise or fall
• receive an alert.

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Civil Defence Bay of Plenty director of emergency management Clinton Naude urged everyone in the community to understand all of the warning signs.

Naude said an earthquake in the Kermadec Trench, an 1000km ocean trench in the south Pacific Ocean, could generate a tsunami that could reach the Bay of Plenty in less than an hour.

But it could take up to 40 minutes to issue an official warning so it was vital residents knew all of the warning signs.

"For a more distant tsunami, there would be time to send an official warning so it is also important to understand how you can be alerted," he said.

Previously, the message of "long or strong, get gone" was the main focus but emergency managers in the Bay of Plenty urged people to understand all of the warning signs.

Civil Defence emergency management regional manager Clinton Naude. Photo / File
Civil Defence emergency management regional manager Clinton Naude. Photo / File

Naude said tsunamis could be generated by underwater landslides or volcanic eruptions but the largest tsunamis are usually caused by large underwater earthquakes.

"Every tsunami is different, which is why people need to be aware of all the ways they may be warned.

"A long or strong earthquake is still the best natural warning sign that people should respond to, however, some tsunami can be generated where we may not experience long or strong shaking.

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"This is why we need them to be aware of the full range of ways they may be warned and understand that any one of them is a trigger for them to take action immediately," he said.

Eye witness accounts of tsunamis in Japan, Indonesia and Samoa reported that prior to the tsunami arriving there was a sudden rise or fall in sea level before the first wave arrived.

There are now four warning signs to look for in terms of tsunami. Photo / File
There are now four warning signs to look for in terms of tsunami. Photo / File

There were also consistent reports of loud noises, similar to the roaring of a jet plane, coming from the ocean.

One of the national alerting tools, the Emergency Mobile Alert is one of the national alerting tools and phones needed to be capable of receiving the alerts.

The phone also needed to have cell reception and up-to-date software. You don't have to download an app or subscribe to a service.

This would be tested later in the year.

This was also an opportunity for people to discuss with friends and whānau what they would do in the event of a tsunami and practice their evacuation route.

For more information on emergency alerting, visit www.bopcivildefence.govt.nz/be-warned.