Multiple Failure Surfaces Over Dip‐Slip Faults

Abstract

The shapes and locations of failure surfaces in alluvium overlying active dip‐slip faults are studied on the basis of experiments performed in a fault test box. A simple model for predicting primary and secondary failure surfaces in the alluvium caused by unidirectional movement on the bedrock fault is reviewed. This model is employed to evaluate additional failure surfaces produced by fault movement in the opposite direction and subsequent to the initial movement. The shapes and locations of these latter failure surfaces are almost unaffected by the presence of failure surfaces caused by the initial fault movement. Ground surface expressions in alluvium associated with movements on dip‐slip faults are summarized. Three field cases are reviewed and related to the experimental observations and the proposed simple model. This model is used to predict shapes and locations of failure surfaces in alluvium overlying dip‐slip faults. Model predictions compare favorably with observations from the field.