Russian Journal of Earth Sciences
Vol. 6, No. 2, April 2004
Modelling of crust and mantle heterogeneity effects in the theory
of Earth tides
S. M. Molodensky
Abstract
General relations are obtained for the determination of radial and tangential
components of displacements and gravitational potential variations at the
Earth's surface due to tidal forces for a model with a horizontally
inhomogeneous distributions of elastic moduli. Model calculations are performed
to estimate the effects of local and regional inhomogeneities of elastic moduli
specified in regions of simple configurations on tidal variations in gravity,
tilts and deformations.
As distinct from gravity data, data on tidal tilts and deformations can provide
significant constraints on local inhomogeneities of elastic moduli in the
immediate vicinity of an observation point. Results of model calculations show
that the phases and amplitudes of tidal tilts and deformations change by 10-15%
in the vicinity of a soft inclusion in which the shear modulus is smaller than
its value in the surrounding medium by 20-30%. Anomalies of such a contrast can
be detected over several months of continuous tidal observations.