Most of Japan's local governments utilize municipal disaster-management radio communications systems to
communicate information on disasters or terrorism to residents. The national government is progressing in efforts toward
digitalization by local governments of these systems, but only a small number (approx. 10%) have introduced such
equipment due to its requiring large amounts of investment. On the other hand, many local governments are moving
forward in installation of optical fiber networks for the purpose of eliminating the "digital divide."
We herein propose a communication system as an alternative or supplement to municipal disaster-management radio
communications systems, which utilizes municipal optical fiber networks, the internet and similar networks and
terminals. The system utilizes the multiple existing networks and is capable of instantly distributing to all residents, and
controlling, risk management information. We describe the system overview and the field trials conducted with a local
government using this system.