Your phone may be among the billions of devices worldwide that already serve as an earthquake early-warning system in dozens of countries.

Since launching in 2020, Google’s Android Earthquake Alerts system has expanded to enable 2.3 billion Android phone and smartwatch users to receive alerts about seismic shaking nearby, compared with 300 million people who may get such alerts from other sources, according to a new study by researchers at Google. But the phones aren’t just delivering warnings – their sensors also help detect earthquakes.

“Billions of Android devices work together and act as mini-seismometers to create the world’s largest earthquake-detection network,” says at the University of California, Berkeley, who is also a visiting researcher at Google.

The system developed by Allen and his colleagues analyses vibrations detected by accelerometers in Android phones and smartwatches. Together, this network of sensors can indicate how large an earthquake is and which phone users are close enough to danger to receive a warning message.

Google’s system notifies people when it detects an earthquake with a magnitude of 4.5 or greater. But the system “cannot detect all earthquakes” because it requires that a large enough number of phones will be close enough to the quake, says Allen. For example, it doesn’t detect earthquakes originating from most mid-ocean ridges, although it can detect seismic events occurring tens to hundreds of kilometres offshore.

One of the greatest challenges has been to quickly and accurately determine the magnitude of each seismic event. The researchers have improved the system’s earthquake-detection algorithm over the years by developing regional models to better represent local tectonic movements and accounting for varying sensor sensitivities among different Android phones.

Free newsletter

Sign up to The Earth Edition

Sign up to newsletter

Google’s global system is now about as accurate as the ShakeAlert system that covers the US West Coast and the Japan Meteorological Society’s earthquake early-warning program, says Allen. He notes that Google’s project is intended to supplement, rather than replace, seismometer-based systems like these – it even incorporates and delivers ShakeAlert warnings for people on the West Coast. “But the reality is that many earthquake-prone regions don’t have the regional seismic networks necessary to provide warnings,” says Allen.

Google’s system provides a “unique source of information” for countries without earthquake early-warning systems, says at Western University in Canada, who isn’t involved in the initiative. It also reaches more people in total, even when other national or regional alert systems are available, he says.

The system currently provides alerts to , including the US but not the UK. “We’ve generally focused on countries that have larger historical seismic risk while not having an existing earthquake early-warning solution,” says at Google.

According to the new study, which analysed the program’s performance and accuracy, the system had issued alerts for 1279 seismic events as of March 2024, with just three false alerts. Two of those false alerts involved thunderstorms and one was triggered by an unrelated mass notification event that vibrated multiple phones. The team has since updated the detection algorithm to avoid such false triggers.

Most Android devices are opted in to participate in the phone-based seismometer network and receive alerts about nearby earthquakes by default, although users can change both of these settings. In a Google user survey, more than one third of the system’s participants received phone alerts before they felt any shaking – and most people who got alerts described them as very helpful.

If Android phone users do remain signed up for alerts, these come in two types. More urgent Take Action alerts are designed to spur people to take protective actions, such as “drop, cover and hold on”. But they often provide just a few seconds’ worth of early warning because they don’t go out until the system predicts strong shaking. In contrast, the less intrusive Be Aware alerts, which provide more general information, can arrive tens of seconds before phone users feel an earthquake.

“The physics of earthquakes dictates that there will be less warning prior to stronger shaking than weaker shaking,” says Stogaitis. “But we continue to explore modifying our alerting strategy to improve the warning times in future earthquakes.”

Do you find yourself distracted at work, turning to your smartphone for a bit of mindless scrolling? One solution is to put your phone out of reach – but unfortunately, it seems this may not work.

“People turn their phone upside down, hide it under a notebook, sometimes you see the slightly fatalistic ‘throw it over my shoulders behind me’,” says at the London School of Economics. He has previously studied phone use and found that people interact with their devices

To see if this distraction can be avoided, Heitmayer recorded 22 university students and office workers, aged between 22 and 31, working as usual on their laptops on a desk in a private room. On one day, the participants kept their phones within arm’s reach. On a second, they kept their phone on a second desk 1.5 metres away, meaning they had to stand up to check it.

Heitmayer found that the volunteers spent an average of 23 minutes carrying out leisure activities on their phone on the first day, but spent 16 minutes when their devices were further away. Yet they didn’t work for any longer on the second day – instead, the participants simply spent more time carrying out leisurely activities on their laptop, mostly on social media. “You can use the phone less, but this whole scrolling on social media for longer than you intended just migrates to the laptop,” says Heitmayer.

“This shows that what’s distracting is not the device in itself, but more the underlying activity, so maybe social media or gambling or whatever people do online,” says at Erasmus University Rotterdam in the Netherlands.

However, she points out that larger studies tracking people in their normal working environment are needed to verify these initial results. “It’s an experimental lab study – people usually have other people around them, and their lives are much more dynamic than this setup, so this could change how they work,” says Derks.

Free newsletter

Sign up to The Daily

Sign up to newsletter