Abstract
The results of geodetic surveys (triangulation, leveling, gravity, magnetism) before and after the in-land type earthquake concerning the earthquake area of central part of Gifu prefecture, Sept. 9, 1969 (φ=35°47', λ=137°04', depth 0-5 km, M=6.6, Japan Meteorological Agency) is reported, referring to seismic data in this area. By comparing the crustal movement of pre-, co-, and post earthquake deduced from these data with the Niigata earthquake (1964) 's pattern, it is clarified that the priorearthquake phenomena exist in this earthquake as 6-stage or dilatancy stage proposed by Scholz et al. [15] and others. Migratory crustal movement is suggested to cause to occur the new earthquake of M=6, 0, Aug. 31, 1972 in the middle point between the Kitamino earthquake (1961) and this earthquake, transforming a part of stress energy into density variation energy.
