Users who have the beta version of iOS 5 have reported that a new option in the settings for the Notification Center will provide Japanese users with earthquake warnings. The instruction also warns users that turning on this setting will decrease the battery life of their iPhone. Japan has an online earthquake system, which provides warnings from anywhere to two minutes right before a quake. That time is vital for getting people to safety. The system can already send text messages to cell phones. This feature on the iPhone is battery draining because it is always connected to Japan's earthquake warning system.
That's the setting that will allow you to receive earthquake warnings
Apple showcased iOS 5 at the company's Worldwide Developers' Conference, earlier this year and so far, there hasn't been an exact release date yet. It is rumoured that the update will be made available when the new iPhone comes out this year, which also is rumoured to be in either September or October.