Previously the eight-month-old system has only been available in parts of the US.
The Android Earthquake Alerts System uses the sensors in Android phones (that is, nearly every phone that's not an Apple iPhone) to detect quakes.
The free system is enabled on every phone unless a user opts out.
If there is a possible quake, then "near-instant" alerts are sent to all Android phone users in the immediate area. All Android users will receive the alerts unless they opt out in device settings.
Quake information will also be available to all comers who search Google for "Earthquake near me."
Google launched its Android Earthquake Alerts System in August 2020, in partnership with the United States Geological Survey (USGS) and powered by ShakeAlert (developed by the USCS), which made alerts available for Android users in California.
This feature recently expanded to users in Oregon and will be rolling out in Washington this May.
Early warning alerts in New Zealand and Greece work by using the accelerometers built into most Android smartphones to detect seismic waves that indicate an earthquake might be happening, Google said.
"If the phone detects shaking that it thinks may be an earthquake, it sends a signal to our earthquake detection server, along with a coarse location of where the shaking occurred," Google product manager Boone Spooner said.
"The server then takes this information from many phones to figure out if an earthquake is happening, where it is and what its magnitude is."
Dr Gill Jolly, team leader for Natural Hazards and Risk at GNS Science, said any innovation that could build New Zealand's resilience to earthquakes is welcome, and the Google product would complement GeoNet's systems.
Warnings are sent by the National Emergency Management Agency (aka Civil Defence), which can push text messages to people in at-risk areas.
Through its website and app, GeoNet also offers crowdsourced "Felt" reports, displaying where people experienced a shudder around the country.
GNS Science's National Geohazards Monitoring Centre monitored all four geohazard perils, earthquake, tsunami, landslide and volcano, around the clock, she said.
"GeoNet continues to be the definitive source of earthquake information for New Zealand.
"[But] we will follow the progress of Google's pilot with interest. We welcome any innovation that helps build Aotearoa New Zealand's resilience to earthquakes."
University of Otago's acting director for the Centre for Sustainability, Caroline Orchiston, said Google's system alongside GeoNet's resources meant New Zealand had "a couple of tools in the toolbox" now.
"There are other products on the market in terms of looking at different ways of locating earthquakes using different systems.
"This is just another one of those but it looks like a really promising way for quite a general part of the population with Android phones to basically crowdsource data, so I think it will be useful.
"It doesn't include everyone, not everyone owns an Android phone, for example. I think we will still rely on our pretty good network seismometers around the country that GeoNet looks after - I think we have a couple of tools in the toolbox now."
