A NOTE ON THE ASSUMPTIONS MADE WHILE COMPUTING THE POSTSEISMIC LITHOSPHERIC DEFORMATION

The postseismic lithospheric deformation is usually explained as visco elastic relaxation of the coseismic stresses. In general, for computin g the postseismic deformation, the shear modulus (mu) is relaxed, keep ing either the bulk modulus (k) or the Lame parameter (lambda) fixed. It is shown that the two assumptions yield significantly different res ults. The assumption k = const. implies that the medium behaves like a n elastic body for dilatational changes which can be justified on phys ical grounds, but such a justification cannot be given in the case of the assumption lambda = const.