Credit: © 2007 AGU

Pervasive deformation of the Asian continent has hitherto been explained by either of two forces: those resulting directly from the collision with the Indian plate and the subduction of the circum-Asiatic oceanic plates — the plate boundary forces — and those related to the buoyancy that keeps the huge Eurasian plate afloat on the weaker underlying layer of the Earth's mantle. Recent modelling suggests that the deformational pattern can best be explained by a combination of these forces.

Mathilde Vergnolle from the Centre National de la Recherche Scientifique, France and colleagues1 used a series of numerical models aimed at reproducing the displacement directions and velocities of various parts of the deforming Asian plate, as determined by the latest global positioning system data. Model inputs included the geometry of the plate boundary, the distribution of faults in Asia, and the thickness and other physical characteristics of the crust and mantle part of the Eurasian plate. Models combining plate boundary as well as buoyancy forces do a much better job than those invoking only one of the two forces.

The movement of the eastern parts of China further towards the east and southeast — previously attributed to the squeeze from India pushing up against Eurasia — is in fact due to a pull to the east, perhaps because of the collapse of the thicker part of the continental area towards the thinner oceanic basins.