Android is becoming a worldwide earthquake detection network

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Google 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.

“The server aggregates data from many phones, all of them in one area, and determines if an earthquake is happening or not.”

“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.”

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.

Before the stage where it sends alerts, Google will start by simply putting earthquake information in search results. Before the stage where it sends alerts, Google will start by simply putting earthquake information in search results. Image: Google

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.”

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.”

“There’s many factors that will impact how many phones you need. I think the key is we don’t need super precise information but we do need a decent amount of information.”

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.”

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.

“We have many seismologists within the team who are literally just embedded with us,” Stogaitis says. That includes Richard Allen, “who spent most of his career on earthquake early warning [systems] and who did a lot of the design of ShakeAlert system, and who’s also kind of built a phone-based earthquake detection system in the past as well.”

Allen’s MyShake app is an earlier example of a system like this — but the difference now is that Google can build that detection directly into Android and it can do it at Google’s scale. (Unlike Google’s system, MyShake works on iPhones.)

Google’s intention is to have differing levels of alerts for different earthquakes. It has consulted with seismologists not only on the design of the core system but also on how the alerts should appear. The goal is to “convey information kind of as quickly as possible in a short amount of time so that users can understand that they need to react very quickly to an earthquake without reading a huge wall of text,” Stogaitis says.

Google’s alerts will include very basic safety recommendations. Google’s alerts will include very basic safety recommendations. Image: Google

Over the long term, Google hopes to create an API based on its earthquake detection system. It doesn’t plan on using this system on iPhones, but if the API comes out then Apple would be free to use it. More interesting, though, is what other systems would benefit from an earthquake detection API.

For example, somebody could build something that automatically stops an elevator at the next floor and opens the door so that people can get out before the wave comes. And you can turn off gas valves automatically, you can have something that stops medical procedures, or open the door to fire stations ahead of time. That’s a common problem in earthquakes where fires are a big deal and firefighters often just can’t get out. So, you can build something that does that. Airplanes can stop landing as they’re doing this, abort their landing. Trains can be slowed down. There’s an entire ecosystem that could be enabled by using this Android-based detection and having it sort of just publish server-side so that others can plug into it.

The stakes for such a system would be incredibly high — and the responsibility for maintaining that system would be equally high. So that API is a long way off. Google’s plan is to minimize false positives and tune the system right now. Google also had to put in extensive effort to ensure its notifications wouldn’t overwhelm cellular networks. Sending out a ping to every Android phone all at once has the potential to clog up those airwaves.

“The thing about earthquakes is they move really, really fast … So, we can’t really put a human in the loop.”

Google will be rolling this system out via Google Mobile Services, so it won’t require a full operating system update. This means both the detection system and the alerts should work on the vast majority of Android phones in use today. (It also means that these services won’t be coming to China anytime soon, as Android phones in that country do not use Google’s services.)

Google is starting to provide earthquake alerts in California right away, using the existing seismometer network. Earthquake data will also begin showing up in Google searches soon as well. As for the warnings and alerts based on the data aggregated from Android phones, that will take a bit more time. Google says that if a region has an existing earthquake detection and warning system, its preference is to use that rather than the phone-based system.

“Basically, there are hundreds of millions of people around the world that live near earthquake fault zones,” Stogaitis says, “and that’s something that we think we can help with.”

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