Investigation of active crust by means of geodetic surveys in Japan



The Geographical Survey Institute has conducted the repetition of geodetic surveys, the periods of which are 5 years in the first-order leveling and the first- and second-order magnetic surveys, and 10 years in the first-order triangulation and second-order gravity survey in all of Japan. Besides these, 12 quadrilaterals are intended to be reoccupied every two years. These works are expected to be useful for the prediction of large earthquakes through clarification of the detailed behavior of the crustal activities of the Japanese Islands.