People will receive a test message on their mobile phones today in a national test of the Emergency Mobile Alert system.
A preview of how the emergency mobile message will look on an iPhone.
Source: Civil Defence
The test message will be sent between 6pm and 7pm.
The new system is being implemented by the Ministry of Civil Defence and Emergency Management.
"There's no need to sign up or download an app - all you need is a mobile phone that is capable of receiving Emergency Mobile Alerts, and a network signal," says Ministry of Civil Defence and Emergency Management director Sarah Stuart-Black.
Those people whose mobile phones are capable of receiving the alerts can expect to hear a loud, penetrating sound, and a notification will display.
It is expected that about one third of mobile phones, or about two million, will be able to receive the alert.
The number will continue to rise as people replace their devices over time.