Calais, E., and S. Amarjargal, New constraints on current deformation in Asia from continuous GPS measurements at Ulan Baatar, Mongolia, Geophys. Res. Letters, 27, 1527-1531, 2000.
Using GPS data continuously recorded at a permanent site in Ulan Baatar (Mongolia) between 1995 and 1998, we find a velocity 6.4±1.6 mm/yr in a N125±30° azimuth with respect to Eurasia. This result, together with the GPS-derived velocity at other sites in northern China, indicates eastward motion of the Amuria/North China block at 6-10 mm/yr relative to Eurasia.
The small differential motion between the Amuria/North China and South China blocks implied by these geodetic results (less than 5 mm/yr) is difficult to reconcile with the geological rates of 10-15 mm/yr found on some of the major strike-slip faults that separate these two blocks. The velocity of the Amuria/North China block relative to Eurasia does not agree with a model where eastward translation of a rigid south China block dominates, that requires a faster velocity for south China and slower velocity for north China, but are in better agreement with models where crustal thickening dominates lateral extrusion.
The current motion of the Amuria/North China block is significantly faster than the predictions of deformation models of Asia that assume full coupling in the India/Eurasia collision zone, zero-coupling along the Pacific subductions, and neglect gravitational forces. This suggests that the India/Eurasia collision is not the only process currently driving deformation in Asia, but that other mechanisms, such as far-field contribution of subduction processes and gravitational forces may also significantly contribute to intracontinental deformation.