Facebook is introducing Safety Check, a tool that people can use when major disasters strike and check on others. Here is how it works. Once activated after a natural disaster and if you are is in the affected area, you will receive a Facebook notification asking if you’re safe.

Facebook will determine your location by looking at the city you have listed in your profile, your last location if you’ve opted in to the Nearby Friends product, and the city where you are using the internet.

If you’re safe, you can select "I’m Safe”"and a notification and News Feed story will be generated with your update. Your friends can also mark you as safe.

If you have friends in the area of a natural disaster and the tool has been activated, you will receive a notification about those friends that have marked themselves as safe. Clicking on this notification will take you to the Safety Check bookmark that will show you a list of their updates.

Safety Check, which will be available globally on Android, iOS, feature phones and desktop.