Public warning systems

Sirens and stingers

Napier has public alerting sirens and we have a suite of transportable stingers that can be used to alert the public and transmit messages via a megaphone. The public alert siren in Napier is five minutes long (10 seconds on, 20 seconds off – 10 times). We flick test these occasionally.

If you hear a Civil Defence siren alert or stinger message:

• seek further information
• tune it in to a local radio station, check this website and emergency updates, or go to our Facebook page
• follow any advice given

We will never use sirens and stingers to warn for a local-source tsunami in Hawke’s Bay. The only warning for a local-source tsunami is a large earthquake. If an earthquake is longer than one minute, or could knock you off your feet, immediately evacuate away from the coast. Remember: If an earthquake is LONG or STRONG, get gone.

The National Emergency Management Agency, GNS Science and New Zealand’s Tsunami Working Group all agree with international best practice – that tsunami sirens are inappropriate as a warning system in regions such as Hawke’s Bay that are subject to local-source tsunamis.

This is for several reasons:

• The time it takes for scientists to determine whether an earthquake has created a tsunami threat and send out official warnings can be longer than the time it takes for a local-source tsunami to reach our coast. A tsunami could arrive in as little as 10 minutes.
• The earthquake damage itself can make the sirens fail – in a survey after the 2011 earthquake and tsunami in Japan, 17 out of 27 affected municipalities reported their tsunami alert transmission system failed from power cuts or earthquake damage and did not function properly at the time of the disaster.
• International research (especially from Japan) shows the existence of sirens creates delays as the public wait to be warned by the siren, rather than making a decision to respond to the earthquake itself.
• In other cases, sirens have led to people ignoring them or delaying evacuation due to false alarms. This is especially true in places where the sirens are triggered automatically without a person making a decision.
• There can be problems with the effectiveness of the sirens through audibility (especially when it is windy, whether you are indoors or outside), which people tell us about every time the sirens are tested around the country. If you didn’t hear it but thought you should, you might not evacuate.

Don’t rely on others to tell you want to do. The best and most reliable warning system for local-source tsunami along the east coast is the natural warning itself – the ground shaking for longer than a minute, or so strongly that it’s hard to stand up. It doesn’t require power, or a smartphone; it just needs you to react to mother nature’s blunt and obvious warning and immediately evacuate.