Surface deformation in a crustal setting with a long surfaced non-uniformity

Abstract

Many heterogeneous zones in the crust which lie at the surface can be approximated geometrically as long horizontal cylinders of half elliptical cross-section with depth. For example, these include alluvially filled valleys and formerly active fault zones. A two-dimensional elastic model giving the quasi-static surface deformation for this class of crustal rigidity profiles is developed. The applied stress is assumed to be a remotely applied uniform shear. Calculations using this model show local strain and deformation excursions from expected data assuming the conventional uniform rigidity half-space model. The magnitude of these anomalies can be quite large depending on the values of the heterogeneous zone's compliance and dimensions. The anomalies were found to be local since the horizontal extent of their pertubation field was at most only a few times the depth of the heterogeneity.