飛騨山脈焼岳のGPS地殻変動観測と噴気孔温度観測（1992-2008）

Since 1992, crustal deformation at and around the Yake-dake volcano in the Hida mountains, central Japan, has been measured by the geodetic survey with a Global Positioning System (GPS), and the temperatures of fumaroles at the Yake-Dake volcano have been measured with a radiation thermometer since 1993. The GPS network, established at and around the Yake-dake volcano, Hida mountains, and in the Matsumoto basin, consists of five observation stations: Yake-dake, Kamikochi, Nakao, Kurio, and Shinshu University (Matsumoto city). The Yake-dake station is located at the Yake-dake observation platform, which is near the top of the mountain, and the Kamikochi and the Nakao stations are located at the foot of the volcano. The Kurio station is located at the middle foot of Mt. Nishihotaka-dake, and its altitude (2199m, WGS84) is almost the same as that of Yake-dake station (2176m). Observed data were analyzed using the broadcast ephemeris and the default meteorological values with the double difference technique. (改行) From the present GPS measurements, it was found that, for the baseline between Yake-dake and Kurio, about 3.7km in length in the north-south direction, the temporal change of baseline length during the twelve years from 1996 to 2008 contracted -7cm (-20ppm), and the variation of upheaval at Yake-dake became +3cm during the same period, when fixed at Kurio (Nishihotaka-dake). On the other hand, for the baseline between Kamikochi and Nakao, located at the foot of the Yake-dake volcano, about 5.3km toward the northwest-southeast direction, the temporal change of baseline length became within 1cm (2ppm) during the sixteen years from 1992 to 2008. Crustal deformation at and around the Yake-dake volcano during the last sixteen years, 1992-2008, and temperatures of fumaroles at the Yake-dake volcano during the last fifteen years, 1993-2008 are reported and discussed in the present study