Topographic effect on tilt, strain, and displacement measurements

Deformation and stress fields are locally modified by the presense of topography. An approximate analytical method is used to give simple expressions for the effect of arbitrarily shaped topography on vertical, horizontal, and surface tilt measurements. This provides a means of making corrections to observations without the use of finite element techniques. Corrections to tilt fields are found to be directly proportional to the local slope of the topography. Comparison is made between expressions for tilt and those for strain and displacement. Although the topographic effects on secular tilt, strain, and vertical displacement are not yet measurable, we emphasize that the topographic effect on precision tidal tilt and strain measurements can be significant.