Deformation of landslide surfaces as indicators of movement processes

Abstract

Deformation that occurs at the surface of a moving landslide can provide insight into landslide kinematics and stability analysis. The deformational data, cumbined with subsurface information on geometry and pore pressures, can lead to different strategies for remedial treatment depending on the size and geometry of the driving and resisting elements of the landslide. Displacement of points on the surface of the landslide can be measured using an analytical stereoplotter and different sets of aerial photography. The scalar magnitudes of the displacement vector are used to draw contour map of the displacement. Changes in displacement can be used to compute average one-dimensional strain at the landslide surface. Examples from the Twin Lake landslide are discussed. The observed pattern of deformation shows large extensional strain in the upper part and large compressive strain at the toe. A neutral area separates driving from resisting parts of the landslide.