Tilt of Yake-Dake Volcano Observed by Precise Leveling and its Relation to the Seismic Activity (1977-1981)

Abstract

A small array network for precise leveling was set on Yake-Dake Volcano in 1977. Length of this leveling line is 20-65 m. Leveling has carried out once a year in autumn season. Remarkable tilt changes of inclined northward about 80μ radian was observed during the period from 1977 to 1981, which correspond to a relative upheaval of the summit of Yake-Dake. The tilt rate was increased every year and reached to 31μ radian per year in 1980. On the other hand, number of earthquakes near the volcano was also increased year by year. The tilt movement is very close to the seismic activity of the volcano.