During a major disaster, Facebook users can let their friends and family know they are safe by using the new Safety Check tool.
When the tool is activated and Facebook determines that a user may be in an area where a natural disaster occurred, the social network will send a notification asking if the user is safe. If the response "I'm Safe" is selected, Facebook will create a post and share it on the user's news feed, telling friends they are out of peril. Friends too have the possibility to mark someone as safe.
Facebook determines a user's location by looking at the city listed in their profile, their last location if they've opted in to the Nearby Friends service, and the city where they are using the Internet, presumably derived from their IP address. If the location is wrong the user can tell Safety Check they are not in the affected area.
If your friend is in a disaster area and the tool has been activated, you will receive a notification about those friends that have marked themselves as safe. Clicking on the notification will show a list of their updates.
Safety Check was created after the great earthquake and tsunami in Japan in 2011. To make it easier to communicate, Japanese Facebook engineers built a disaster message board, a first version of Safety Check.
Facebook CEO Mark Zuckerberg launched the service during a visit to Tokyo on Thursday.
"It's meaningful to be in Tokyo to announce this because the great earthquake and tsunami a few years ago inspired us to build the first version of this for Japan," said Zuckerberg, in a posting to his personal Facebook page.
Facebook isn't the first web giant to launch such a service. As part of its Crisis Response services, Google has previously activated its "Person Finder" service during such events -- including the 2011 quake -- allowing people to provide information about survivors of major natural disasters.
Loek is Amsterdam Correspondent and covers online privacy, intellectual property, online payment issues as well as EU technology policy and regulation for the IDG News Service. Follow him on Twitter at @loekessers or email tips and comments to email@example.com