Your Android phone can notify you of an earthquake seconds before it happens. Here’s how

If you live in an area prone to earthquakes, you're probably used to feeling the earth shake without warning. But in recent years, technology has allowed governments and independent companies to create earthquake warning systems.

These systems, like Google's Android Earthquake Alerts System, can't foresee an earthquake, as that technology doesn't exist yet. But it can give people a seconds-long warning to take action to prepare. 

On October 25, a 5.1-magnitude earthquake occurred in the San Francisco Bay Area. Twitter users thanked Google for the warning, saying they received a notification of the oncoming earthquake just a few seconds before they could feel the ground shaking.

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Google's earthquake detection is available worldwide but is more advanced in California, Oregon and Washington, where more seismometer systems can communicate with Google's servers. 

Google's earthquake alert uses data from Android phones and the phones' accelerometers, which are small sensors that, when used together, can detect an earthquake happening right before it hits. The accelerometers in phones are how Android phones can notify people in areas without seismometer systems of an earthquake.

Those sensors send signals to Google's earthquake detection server, along with a rough calculation of the earthquake's location, and then Android users are notified of gound-shaking activity.

Technology is constantly evolving to help keep us safe, like Google's earthquake detection system and Apple's crash detection. iPhone users can also get earthquake alerts — via iPhone Settings in some locations, or from a third-party app. This week's quake drew comparisons between Android and iPhone alerts.

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David Kleidermacher, a member of Google's security team, hints that Google subscribes to the “power of open,” and other companies don't. He mentioned that Apple didn't notify an iPhone user in his office of an earthquake until after it happened. 

Google says seismometer systems are expensive to build and use, so the solution is to use Android phones as mini seismometers. But as Robert de Groot, a member of the ShakeAlert operations team, told Wired, for phones to work as earthquake detectors, people have to be close to the earthquake.

As Google refines the technology, they hope to notify people of an earthquake with more seconds between the notification and an active earthquake. The technology is still new and underdeveloped, so it could be a while before people have even a minute to take cover.