Facebook on Thursday announced a new feature aimed at offering its users the option to make a very specific kind of update: a check-in to let family and friends know they're safe after a natural disaster.

Safety Check, as the new feature is called, gives Facebook users the option to check in with one-click to tell loved ones that they're out of harm's way when there's a natural disaster. Facebook chief executive Mark Zuckerberg announced the feature in Tokyo, Japan. Safety Check was first inspired by the reaction Facebook users had to the 2011 tsunami that devastated the northeastern Tohoku region.

“During crises the internet can be a powerful tool for sharing vital information and connecting people with their loved ones," said Mark Zuckerberg, Facebook's founder and chief executive in a statement. "The Safety Check tool is designed to serve the Facebook community when it matters most.”

When there's a disaster on that sort of scale, Facebook will now ping users who've enabled location services with a notification asking them to update their status on Facebook. Only friends will be able to see these posts, which simply let people know that an individual is safe. Users in an area affected by a disaster can also mark other friends in their network as safe.
Answering that prompt then generates a wall post that a user's friends can view, comment on and share with others as needed.

Facebook employees Peter Cottle and Sharon Zeng looked at the on-network reaction to the catastrophic tsunami, as well as other disasters such as 2013's typhoon Haiyan, the recent typhoons that have pummeled western Asia and even the earthquake that rocked Napa Valley in August.

"We've been watching all these events and, put together, they've taught us how people use Facebook and how it can be a useful tool in many of these situations." said Marcy Scott Lynn, who works on Facebook's sustainability and privacy programs. For example, after many natural disasters, cellular networks often get clogged with calls and texts after a disaster, putting strain on the networks at a time when they need to be clear for emergency calls. This sort of feature, the company said, could be an alternative to let loved ones know you're safe without having to make a call.

Lynn said she knows that the feature won't be ideal for every situation, but Facebook hopes to learn over time when best to deploy the tool. Factors such as the scope, impact and duration of a disaster will play into the company's decision-making.