火山性地殻変動(V) ―桜島火山における地殻変動観測―

Abstract

Crustal deformations accompanying with the recent volcanic activity in the vicinity of VolcanoSakura-jima are studied from the results of continuous instrumental registrations of crustal deforma-tions and the repeated precise geodetic levellings.The analyses of horizontal pendulum type tiltmcters during the period from 1964 to 1970 sho-wed the mean tilting rate of 27" /year of dip to the NNW direction at Kitadake station and 3" /yearof dip to the SE direction at Harutayama station. Secular variation of tiltgrams at Hakamagoshistation showed mean tilting rate of 7" /year of dip to the SSE direction during the period from 1962to 1965, but 2" /year of dip to the west during the period from 1965 to 1970.As a parameter of volcanic activity, three monthly total numbers of volcanic explosions at Mi-namidake crater were compared with the elevation change of B. M. 29 and B.M. 111. There werefairly close relations between the elevation change of B. M. 111 and the recent volcanic activity atVolcano Sakura-j ima.