One of the major earthquakes named "Chuesu-oki Earthquake" was happened in Niigara Prefecture, central part of Japan on July 16, 2007. Since four days after the earthquake, our researchers ' team has joined volunteer coordination activities as so called "information volunteer" by using WIDIS (Wide area Disaster Information Sharing system) which is a kind of web based geographical information system. Our activity includes 1) making daily reports on the activity and disclosing information by using WIDIS (http://saigai.jp/), 2) building and updating database for affected houses, 3) coordination activities of volunteers to the disaster victims. WIDIS has been actually used for all aspects of these activities. Through these experiences, it became clear that G-WIDIS can be effectively used to coordinate disaster relevant information between each volunteer centre which will be placed in afflicted cities and towns. © 2008 IEEE.