Android phones earthquakes, Google adds California’s earthquake early warning system.

GoogleGoogle is creating a worldwide, Android phone-powered earthquake alert system. The first part of that system is rolling out today. If you opt in, the accelerometer in your Android phone will become one data point for an algorithm designed to detect earthquakes. Eventually, that system will automatically send warnings to people who could be impacted.

It’s a feature made possible through Google’s strengths: the staggering numbers of Android phones around the world and clever use of algorithms on big data. As with its collaboration with Apple on exposure tracing and other Android features like car crash detection and emergency location services, it shows that there are untapped ways that smartphones could be used for something more important than doomscrolling.

Google is rolling out the system in small stages. First, Google is partnering with the United States Geological Survey and the California Office of Emergency Services to send the agencies’ earthquake alerts to Android users in that state. Those alerts are generated by the already-existing ShakeAlert system, which uses data generated by traditional seismometers.

“It’d be great if there were just seismometer-based systems everywhere that could detect earthquakes,” says Marc Stogaitis, principle Android software engineer at Google. But, he continues, “that’s not really practical and it’s unlikely to have global coverage because seismometers are extremely expensive. They have to be constantly maintained, you need a lot of them in an area to really have a good earthquake early warning system.”

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So the second and third stages of Google’s plan will be powered instead by Android phones. The company is proceeding fairly cautiously, though. In the second stage, Google will show localized results in Google searches for earthquakes based on the data it’s detecting from Android phones. The idea there is that when you feel an earthquake, you’ll go to Google to see if that’s what you felt or not.

Finally, once it has more confidence in the accuracy of the system, Google will begin actively sending out earthquake warnings to people who live in areas where there are not seismometer-based warning systems.

Stogaitis says that the information collected as part of this program is “de-identified” from users and that Google only needs “coarse” location information for it to work. Both the earthquake alerts and the detection system are opt-in, as well. “What we really need for this is just these little mini seismometers that are out there,” Stogaitis says. “We don’t need to know anything about the person itself that’s sending it because that doesn’t matter.”

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An Android phone can become a “mini seismometer” because it has an accelerometer — the thing that detects if you’ve rotated it or not. Android’s system uses the data from that sensor to see if the phone is shaking. It only is on when an Android phone is plugged in and not in use, to preserve battery life.

“We figured out [Android phones are] sensitive enough to detect earthquake waves. As an earthquake wave goes through, they’re able to detect them and usually see both key types of waves, the P wave and the S wave,” Stogaitis says. “Each phone is able to detect that something like an earthquake is happening, but then you need an aggregate of phones to know that for sure that it’s an earthquake happening.”

The P wave (primary wave) is the first and fastest wave sent out from the epicenter of an earthquake. The S wave (secondary wave) is slower but can be much bigger. Google’s system is able to detect both. “Often people won’t even feel the P wave because it’s just smaller, while the S wave tends to cause a lot more damage,” Stogaitis says. “The P wave can be something that tells you to prepare for the S wave.”

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That data is processed in classic Google fashion: using algorithms on the aggregated data from thousands of phones to determine whether an earthquake is happening. Where traditional seismometers are expensive and precise, Android phones are cheap and numerous. Google can use Bayesian filters and other algorithms to turn those numbers into earthquake data that’s accurate enough for sending out warning alerts.

Google says its system is capable of locating the epicenter and determining the strength of an earthquake. Even so, the basic physics of those waves means that there are limits to what’s possible, he explains:

The biggest key thing is that the phones that are nearest to the earthquake can help users away from the earthquake know about it. One of the limitations of the system is that we can’t warn all users before an earthquake reaches them. The users closest to the epicenter of the earthquake just aren’t likely to get a warning in time because we’re not predicting earthquakes ahead of time.

That speed also means that Google’s Android-based warning system won’t have a human in the loop, since these warnings will range from “a couple of seconds” near the epicenter to 30 or 45 seconds on the outside.


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