山崎断層安富舂基線網における測量結果(1975-1995)

Abstract

Movements of the Yamasaki fault in the Kinki District, were monitored by employing precise geodetic measurements once a year during the period from 1975 to 1993.The measurements were performed on a small aperture baseline network across the fault. The Hyogo-ken Nanbu earthquake (M = 7.2) occurred on January 17, 1995 in southern part of Hyogo prefecture. Measurements on the network, which is located at the epicental distance of about 60 kim, were carried out in November 1995.Analyzed data for the period of 20 years from 1975 to 1995 show as follows: No remarkable crustal movement due to the earthquake was detected. On the other hand, the values of average secular strain and tilt rates decreased from 1.4 μstrain/year and 0.95 μrad/year in 1975-1986 to 0.5 and 0.16 in 1987-1995, respectively.