Crustal motion in E- and SE-Asia from GPS measurements

Repeated GEODYSSEA-GPS measurements and additional GPS data from the IGS and APRGP97/98 constrain the motion of SE-Asia within a global reference frame. Sundaland i.e. Indochina as well as the western and central part of Indonesia, together with South-China, constitute an apparently stable tectonic block that is decoupled from Eurasia. In the ITRF97 this block moves to the east about an Euler pole approximating that of Eurasia, but with a velocity that is one third higher than the eastward directed movement of Eurasia. With respect to India and Australia the Sundaland-South China block is moving due south. This suggests that a) Sundaland-South China are moving coherently to the East along the boundaries studied and b) the eastward motion of India is compensated by the eastward motion of Sundaland-South China. The current rather homogeneous kinematic behaviour of Sundaland-South China that differs in rate (no more than 5 mm) rather than direction from the movement of N-China differs from the kinematics proposed by different modelling approaches throughout the literature. The data help to constrain locations and behaviour of the active fault zones and give information on the interplate and intraplate deformation in the area.