The Japanese government built an advanced warning system following the devastating earthquake earlier this year. According to 9to5Mac, Apple has integrated said warning system into iOS 5.
Setting the switch to “on” automatically connects the device to the warning system. iOS 5 can apparently alert users of an earthquake anywhere from seconds to minutes before it hits.
The text below the switch notes that a constant connection to the warning system will dramatically affect iPhone battery life.
While it sounds like a great idea, the integration isn’t exactly unique. Yurekuru Call, a third party application available from the App Store, offers the same functionality.