抄録
In order to investigate crustal deformations and to help establish national geodetic datum of countries in the western Pacific region, a continuous GPS tracking network was designed in 1995. We have established 10 stations by November 1997. The network was named as Western Pacific Integrated Network of GPS (WING). In addition, more than 10 stations of International GPS Service for Geodynamics (IGS) have been established by other institutes in this region. Among these sites, data from Marcus, Guam, Chuuk, Palau, Manila, Ishigaki, Taipei, Shanghai, Taejeon, Vladivostok, Usuda and Lhasa were used for crustal deformation analyses in July 1995-October 1996 together with 6 IGS fiducial sites. A fiducial-free approach was employed to obtain the most accurate baseline estimates. To fix the estimated coordinates to the terrestrial reference frame, the Tsukuba IGS site was assumed to be moving about 2cm/yr westward relative to the stable Eurasian continent (Heki, 1996). We find that velocities of Marcus and Chuuk are in good agreement with a rigid plate motion model. On the other hand, Ishigaki and Guam seem to be moving trenchward, suggesting on-going back-arc openings. Stations in the eastern margin of the Asian continent such as Taejeon, Shanghai and Taipei are moving E-ESE relative to the stable Eurasian continent, due possibly to the collision between India and Asia.
