A web-based distributed database system has been developed with an aim o f continuing delivery o f geological
data even i f a large-scale disaster occurs. The distributed database system has an advantage that the system
remains available i f an individual database is down. The software which composes the system is Free and
Open Source Software (FOSS). The distributed database is constructed by combination o f PostgreSQL and
pgpool-II. PostgreSQL is a powerful relational database management system. Pgpool-II has some modes for
management o f a distributed database. It is possible to create a real-time backup on two or more databases
by Replication mode. Data can be split among multiple databases by Parallel query mode. The prototypes of
a distributed database system for sharing borehole data have been successfully implemented by using
Replication mode and Parallel query mode respectively.