This paper studies cases in Japan, focusing on information on volcanic activities as well as other natural disasters. This information is given as an example of scientific communication in times of scientific uncertainty when there is an urgent need for judgments. This paper also considers the usage of volcanic activity information by residents of Kuchinoerabu Island in 2015, from the time their volcano became active to when the island was fully evacuated. The results suggest that it is important not only to establish relationships with highly interested local residents as non-experts, residents who can communicate information, including uncertainties, but also to communicate information among experts, government bodies, and designated members the news media. It is also suggested that a cooperative system of geoparks that feature disasters and benefits would help the volcanic disaster prevention council.