The Actual Plate Kinematic and Crustal Deformation Model APKIM2005 as Basis for a Non-Rotating ITRF

A present-day plate kinematic and crustal deformation model is needed as a reference system for station velocities in the ITRF. The common rotation of all points of the Earth surface has to become zero in order to be consistent with Earth rotation parameters (condition of no net rotation, NNR). To realize this condition, we divide the surface into rigid plates and inter-plate deformation zones. Both, plate motions and deformations are modelled from the observed station velocities. The plate motions are represented by one rotation vector per plate, the inter-plate deformations are computed using a least squares collocation approach. In the APKIM2005, rotation vectors of 17 major plates and deformations in five plate boundary zones (Alps-Aegean, Persia-Tibet-Burma, Alaska-Yukon, Gorda-California, Andes) are estimated. The global integration is done in a 1 degrees x1 degrees grid covering the entire Earth surface. The ITRF2005 velocities result in a rotation of about 0.06 mas/year compared with the non-rotating terrestrial reference frame.