"We want to provide a helpful tool that people can use when major disasters strike, so we've created Safety Check -- a simple and easy way to say you're safe and check on others," Facebook said.
When a major disaster strikes, Safety Check will help you alert family and friends that you're doing fine. It also makes it easy to check on others in the affected area, allowing you to mark that your friends are safe. In terms of privacy, only your friends will see your safety status and the comments you share.
You don't have to participate in any of this if you don't want to. Safety Check is an opt-in feature, and if you do decide to activate it, you'll receive a Facebook notification asking if you're safe when a natural disaster strikes in your area. If Facebook gets your location wrong -- it determines your whereabouts by looking at the city in your profile, your last location if opted in to the Nearby Friends product, and the city where you're using the Internet -- you can mark that you're outside the affected area.
As of right now, Safety Check only applies to natural disasters, like hurricanes and floods, etc. Over time, however, Zuckerberg says it will expand to include more types of issues.