By the Australian Institute for Disaster Resilience
www.facebook.com/about/safetycheck/
Facebook’s ‘Safety Check’ feature gives Facebook users a way to check on family and friends during natural disasters.
During a disaster, Safety Check helps users:
The feature uses the location information provided to Facebook. This includes:
If there is a major event in an area a user has checked in from, Facebook sends a push notification asking if they are okay. Users can specify that they are safe (which will post a status their friends can see) or say they are not in the affected area.
A simple I’m safe / I’m not in the area message (and optional comments) will be visible to people in the user’s friends list.