If the local authorities have an actual life-and-death emergency broadcast to make to the entire area they serve, I suspect they have a more effective means to do this than Twitter. As a matter of public safety, they need to be able to inform everyone, whether they've subscribed or not, and in a way that does not require users to think to check for a notification, or even to have a special device (like a cellphone to receive push notifications). Those extra mechanisms are great and helpful, but they don't replace a true public emergency notification mechanism.
Where I live, the tornado siren, which is beyond extremely loud and mounted high up on a pole in the highest point in the neighborhood, can be used to broadcast PSAs. It screams "THIS IS ONLY A TEST" at noon on the first Wednesday of every month. And you hear it whether you want to or not.
Where I live, the tornado siren, which is beyond extremely loud and mounted high up on a pole in the highest point in the neighborhood, can be used to broadcast PSAs. It screams "THIS IS ONLY A TEST" at noon on the first Wednesday of every month. And you hear it whether you want to or not.