Rockfall

[1] Favourable geology and climate are the principal causal mechanisms of rockfall, factors that include intact condition of the rock mass, discontinuities within the rockmass, weathering susceptibility, ground and surface water, freeze-thaw, root-wedging, and external stresses.

A tree may be blown by the wind, and this causes a pressure at the root level and this loosens rocks and can trigger a fall.

[4] In contrast, lower altitude mountains with warmer climates rockfalls may be caused by weathering being enhanced by non-freezing conditions.

[4] Assessing the propagation of rockfall is a key issue for defining the best mitigation strategy as it allows the delineation of run out zones and the quantification of the rock blocks kinematics parameters along their way down to the elements at risk.

In contrast, active mitigation is carried out in the initiation zone and prevents the rockfall event from ever occurring.

Design guides of passive measures with respect to the block trajectory control have been proposed by several authors.