Real-time capability of GEONET system and its application to crust monitoring



 The GPS Earth Observation Network system (GEONET) has been playing an important role in monitoring the crustal deformation of Japan. Since its start of operation, the requirements for accuracy and timeliness have become higher and higher. On the other hand, recent broadband communication infrastructure has had capability to realize real-time crust monitoring and to aid the development of a location-based service. In early 2003, the Geographical Survey Institute (GSI) upgraded the GEONET system to meet new requirements. The number of stations became 1200 in total by March, 2003. The antennas were unified to the choke ring antennas of Dorne Margolin T-type and the receivers were replaced with new ones that are capable of real-time observation and data transfer. The new system uses IP-connection through IP-VPN (Internet Protocol Virtual Private Network) for data transfer, which is provided by communication companies. The Data Processing System, which manages the observation data and analyses in GEONET, has 7 units. GEONET carries out three kinds of routine analyses and an analysis of RTK-type for emergencies. The new system has shown its capability for real-time crust monitoring, for example, the precise and rapid detection of coseismic (and post-seismic) motion caused by 2003 Tokachi-Oki earthquake.


1. Introduction
2. Requirements for the new system
3. Reinforcement of the observation network
4. Data transmission
5. Structure of the data processing system
  5.1 Real-time Communication Operating Unit
  5.2 Non-real-time Communication Operating Unit
  5.3 Administration System
  5.4 Data Storage Server
  5.5 Routine Analysis Unit
  5.6 Real-time Analysis Unit
  5.7 Display Unit
6. Enhancement of analyses
7. Example of a new GEONET application to the 2003 Tokachi-Oki earthquake
8. Summary