Topographic Effects on the Tidal Strain Tensor

Abstract

Summary A theory is developed to account for the topographic influence on earth tidal strains. Several possible models are considered for the local topography in which the region is assumed to be constructed of uniform, isotropic material only. Using two-dimensional structures, numerical values for the topographic effect are compared for both mechanical modelling and finite element solutions. When the theory is extended in order to analyse a simple three-dimensional structure that has invariant cross section in one horizontal direction the topography is shown to significantly affect not only the magnitude, but also the relative spectral content of tidal strain amplitudes, both of which can be altered by a factor of three or more from the expected smooth topography value. The topographic structure studied is that of the Hillgrove Gorge (Cooney Observatory) on the central east coast of Australia.