To assess the potential of improvements of geodetic accuracy for　the volcanic deformation in mountaneous region, the combination of the GPS　network measurements with a few water vapor radiometers (automated　satellite-tracking type) and D-InSAR analysis aided by the use of corner reflector signals willbe made for two test sites. One is near the New　Trident Volcano in the Katmai Volcanic group and the other　is Karymsky Volcano, Kamchatka. In the test sites, we will deploy several GPS receivers and corner　reflectors, which should be the same period of satellite data acquisition.　The combination of simalteneous data acquisition could provide more　complete set of information for the ground deformation assosiated with the　volcanic and tectonic activities of the Arctic subduction zone.