Geospatial Information Authority of Japan
The Geospatial Information Authority of Japan (GSI), known in Japanese as Kokudo Chiri-in, is the primary national institution tasked with the surveying and mapping of Japan's land. Operating as an extraordinary organ of the Ministry of Land, Infrastructure, Transport and Tourism, the GSI ensures the accuracy of the nation's spatial data. While it was known as the Geographical Survey Institute from 1949 until March 2010, it has retained the GSI initials following its rename.
Headquartered in Tsukuba City, Ibaraki Prefecture, the agency manages a wide array of geospatial responsibilities and also operates the Science Museum of Map and Survey to educate the public on the history and technology of cartography.
Key Facts
- Established: June 2, 1869 (formerly the Ministry of Popular Affairs).
- Headquarters: Tsukuba City, Ibaraki Prefecture.
- Primary Role: National surveying and mapping of Japan.
- Parent Agency: Ministry of Land, Infrastructure, Transport and Tourism.
- Staffing: 671 civilian staff as of 2018.
- Annual Budget: 9,640,335 thousand yen.
Earthquake Precursor Prediction Research
The GSI contributes significantly to seismic safety through its research into earthquake precursors. Since April 1996, the agency has utilized stationary Magnetotelluric (MT) monitoring systems—which measure fluctuations in the earth's electromagnetic field—at the Mizusawa Geodetic Observatory and the Esashi Station.
These systems provide continuous recordings of MT signals that correspond with seismic activity. To support global scientific advancement, the GSI makes this raw geophysical time-series data freely available to the scientific community, facilitating deeper study into the relationship between electromagnetic events and earthquakes. Additionally, the Authority holds a seat on the national Coordinating Committee for Earthquake Prediction.
The Japanese Water Height Reference Point
To maintain consistent elevation measurements across the country, the GSI manages the Japanese water height reference point (Nihon Suijun Genten). This vertical datum is housed in a dedicated structure called the Japanese water height reference point storehouse (Nihon Suijun Genten Hyoko), located in Nagatacho, Chiyoda, Tokyo, in front of the National Diet Building.
Construction of this storehouse began in August 1890 and was completed on December 24, 1891. While the interior of the building is closed to the public, a stone base with a descriptive plaque is available for viewing outside.
Elevations in Japan are measured relative to the mean sea level of Tokyo Bay, a standard known as Tokyo Peil (TP). The term "Peil" is derived from the Dutch language. As of October 21, 2011, the crystal scale on the datum's stone base monument indicates a value of 24.3900 m (80.020 ft) above the mean sea level of Tokyo Bay.
Because referencing a Tokyo-based altitude is impractical for remote regions, 37 islands maintain their own zero points. For example, elevations in Okinawa are measured from the middle water level of Nakagusuku Bay, while those in Miyake are measured from Ako Bay.
Agency Overview Summary
| Attribute | Details |
|---|---|
| Full Name | Geospatial Information Authority of Japan (Kokudo Chiri-in) |
| Founded | June 2, 1869 |
| Location | Tsukuba City, Ibaraki Prefecture |
| Executive | Hiroshi Murakami, Dean |
| Primary Function | National surveying, mapping, and geodetic reference |
Cultural Presence
Beyond its scientific contributions, the GSI has appeared in literature. In Haruki Murakami's novel Norwegian Wood, the GSI is mentioned as the intended workplace of the protagonist's roommate, "stormtrooper." During the late 1960s setting of the novel, the GSI offices were located in Tokyo.
Frequently Asked Questions
What is the GSI?
The Geospatial Information Authority of Japan (GSI) is the national institution responsible for the surveying and mapping of Japan's land, operating under the Ministry of Land, Infrastructure, Transport and Tourism.
What is Tokyo Peil (TP)?
Tokyo Peil is the vertical datum used in Japan, where elevation 0 m is defined as the mean sea level of Tokyo Bay.
How does the GSI help predict earthquakes?
The GSI uses Magnetotelluric (MT) monitoring systems to record fluctuations in the earth's electromagnetic field, providing data that helps scientists study the interaction between EM events and seismic activity.
Does every part of Japan use the Tokyo reference point for height?
No. Because of the distance from Tokyo, 37 remote islands have their own specific zero points, such as Nakagusuku Bay for Okinawa and Ako Bay for Miyake.
Where is the GSI headquartered?
The GSI is headquartered in Tsukuba City, Ibaraki Prefecture, where it also operates the Science Museum of Map and Survey.