Problem Analysis and Solutions of Information Network Systems on East Japan Great Earthquake

East Japan Great Earthquake on March 11 in 2011 caused severe damages over the wide area of Northern Japan. A massive 9.0 earthquake destroyed many buildings and information systems, and a devastating tsunami swept over cities and farmland in the northern part of the country and set off warnings as far away the west coast of the United States and South America. Also, the large-scale earthquake brought the secondary disasters such as blackout, fire, and nuclear crisis. Many information network systems are also severely damaged with the East Japan Great Earthquake. Compared with the recent historical severe earthquakes in Japan such as Hanshin-Awaji Great Earthquake in 1995 and Chuetsu Earthquake in 2004, there were many different types of problems because of the recent highly developed information society. They were the congestion of cellar phone, the lack of fuels and electricity, and so on. In this paper, the problems of information network systems on East Japan Great Earthquake are analyzed, and the solutions of these problems are discussed. Through our network reconstructing activity just after the earthquake, the connection of information network is the most important other than throughput or latency for disaster information system. In fact, satellite system, wireless LAN, and cognitive wireless system were useful for the reactivating network connection in the disaster area.