  The giant Sumatra-Andaman earthquake of December 26 2004 caused permanent
deformations effects in a region of previously never observed extension. The
GPS data from the world wide network of permanent IGS sites show significant
coseismic displacements in an area exceeding 107 km^2. The effects of the
permanent residual deformation field could be detected as far as Australia, the
Phillipines and Japanese archipelagos, and, on the West, as far as the indian
continent. The synthetic simulations of the coseismic displacement field
obtained by means of a spherical model support the hypothesis that a
considerable amount of energy has been released aseismically.
