New Zealand and Greece have today become the first countries to get a Google technology that turns Android phones into a network of earthquake detectors - the better to deliver automated early warnings.
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."
Google described New Zealand and Greece as "two countries that are prone to earthquakes, but lack an early warning system."
But GeoNet, a partnership between GNS Science and EQC, operates a nationwide network of sensors and sends out near-realtime earthquake alerts through its app and social media accounts.
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, Jolly 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."
Postscript: What about privacy?
After this article was first published, one reader asked if Google's new quake alert system represented another privacy invasion by Big Tech. Would data be anonymised?
A rep for Google replied: "Earthquake detection uses the coarse location of the device when shaking occurs. This is city-level data, and does not specify a precise post code,
or street address. There is no personally identifiable information about the user-collected by this detection system.
"The user must have Google Location Services (known as Google Location Accuracy on some versions of Android) on, which can be found in Settings > Location > Google
"If a user has their Location settings off, they will not receive alerts, and Earthquake Alerts can be turned off at any time."