If you're in a disaster area, you can list yourself as safe and well. This is a good idea.
Names can only be searched for by complete address or pre-disaster phone number. This strikes me as semi-reasonable security. There are at least a couple of ways for it to go wrong, but it may be the best possible. Griefers (the kind of practical jokers that Heinlein had in mind) won't find it too difficult to get addresses for false listings, and (to put it mildly), these days we're connected to a lot of people whose full names, addresses, and/or phone numbers we don't know.
Link thanks to pecuniam.