Plate kinematics in the Western Pacific derived from geodetic observations

Plate kinematics have been derived from GPS site velocities spanning Australasia and the western Pacific and define a framework in which deformation fields at plate boundaries can be investigated. The Australian Plate appears to be rigid from Cocos Island in the west to Noumea in the east and incorporating all of the Australian continent. A revision of the angular velocity vector of the Pacific Plate using six site velocities has led to the detection of significant relative motion between the Pacific Plate and sites in northern Papua New Guinea. This provides strong evidence in support of a North Bismarck Plate between the South Bismarck and Pacific Plates and we model the motion of the North Bismarck Plate with the angular velocity vector (45.0°S, 126.4°E, 0.85°/Myr). These new angular velocity vectors model the rigid plate motions of a substantial part of the Australasian and western Pacific regions with an accuracy better than 3 mm/yr.