Structural and kinematic analysis
Figure: Outcrop with several vertical fractures and a well-developed, shallow dipping foliation. (Photo: T. Oppikofer, NGU)
Natural discontinuities in bedrock include metamorphic foliation, cracks, fractures and faults. The orientation of the fracturing is measured in the field using a compass, or by using remote measurements based on high resolution digital elevation models (DEM) and appropriate software tools (e.g. Coltop3D). The structural pattern formed by these discontinuities affects the stability of the mountain, which initially can be assessed using simple kinematic analyses. Such an analysis provides information about the existence of structures that can contribute to the possible movement of an unstable block, and what type of failure might occur (planar sliding, wedge sliding and/or toppling). When mapping unstable rock slopes, NGU generally used the standard criteria of rock mechanics with a few adjustments applicable to unstable rock slopes. See NGU report 2012.029.