The main issue I have with this feature is that as far as I can tell there is no way to opt out. I don't want this feature and I choose not to respond to the notifications I occasionally receive when there is a terrorist event in my city. That leaves me in a bind - unless I tell friends and family who use Facebook that I'm actively choosing not to use the feature, they invariably begin to worry about me when I don't 'mark myself as safe'. This to me is unacceptable.