A web-based distributed database system has been developed with an aim of continuing delivery
of geological data even if a large-scale disaster occurs. The distributed database system has an advantage that the system remains available if 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 of PostgreSQL and pgpool-II. PostgreSQL is a powerful relational database management system. Pgpool-II has some modes for management of 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.