三河地方での光波測量による地殻変動の観測(その1)

抄録

The detecting horizontal strain accumuration with electro-optical means, three geodetic networks; namely Hamanako network (HMN), Atsumi network (ATM) and Kamiyahagi network (KMY), had been set up in the Mikawa region . Since 1972, the authors have been repeating measurement with a Geodimeter model 6 every year . During the tree years survey period from 1972 to 1975, considerably large strains, coparing to some observational errors due to incompleteness of the atmospheric correction or setting of the instrument and so on, have been observed. If these results may be ragarded as significant signals of the ground deformation, the folling conclusions can be noticed: The principal axis of cotracti axis of contraction is in the E-W direction at the Kamiyahagi network, about 60 km inland from the Enshunada coast. On the other hand, ones at the Hamanako network and Atumi network which are located on the coast, are in the NNW-SSE direction. These azimuths of contraction are concordant with the seismic force system of the shallow earthquakes in this region. Strain rates amounting to 20-40×10^-6 in the three years period are about twenty times larger than ones obtained from the precies triangulation data in the period from 188596 to 1973.