Crustal Movement in Japan

Crustal Movement in Japan is the Geospatial Information Authority of Japan's (GSI) public service for monitoring ground movement across the Japanese islands. Japan sits where several tectonic plates converge, producing uplift, subsidence and horizontal movement, from gradual plate-driven deformation to sudden displacement in earthquakes and inflation of volcanoes.

GSI operates about 1,300 electronic reference points (the GEONET network), spaced roughly 20 km apart nationwide, which continuously record GNSS signals, including those of GPS and QZSS (Michibiki). GSI analyses the GPS observations every day to determine each station's precise position, and changes in those daily positions reveal crustal deformation. The current analysis strategy produces a final solution computed with IGS final orbits and a rapid solution updated each morning; the daily record goes back to 1996.

Results are published on the Crustal Movement Information Display Site, which shows displacement-vector maps, baseline-change graphs and coordinate time series for 1-month, 1-year, 5-year and 10-year periods by region, with the underlying numbers downloadable as text or KML files. GSI also issues monthly crustal-movement reports, reports on the deformation caused by individual earthquakes, daily GNSS results around volcanoes and monitoring of slow-slip events, which it reports to the relevant evaluation committees. The information supports earthquake-mechanism research, volcanic-activity assessment, surveying and disaster prevention. Content is free to use under the Public Data License 1.0 with a source citation.