焼岳におけるGPS観測(1992-1994)

抄録

For the purpose of detecting the crustal deformation associated with the volcanic activity, interferometric GPS measurements have been carried out at and around the Yakedake Volcano, central Japan. Five GPS campaigns were conducted in October 1992, August and September 1993, and June and October 1994. The Yakedake GPS network consists of three stations, namely, Kamikochi, Nakao and Yakedake stations. The Kamikochi and the Nakao stations are located at the foot of the volcano. The Yakedake station is located at Yakedake Observation Platform which is close to the top of the mountain, and lies halfway between the Kamikochi and the Nakao stations. Each campaign continued a few days with a daily several-hour session, and was made by using single and dual frequency receivers, namely, Trimble 4000SL, 40005E, and 4000SST. These GPS mesurements clarify that the Yakedake station moved 26±4 mm north-eastward, and subsided 20±5 mm during the period between the first (Oct., 1992) and the fifth (Oct., 1994) campaigns. These results may suggest the possibility of the regional inclination of the Yakedake Volcano. However, no significant crustal deformation associated with the volcanic activity of Yakedake was detected during the period 1992-1994.