MAIN FACTORS RESILIENT INFRASTRUCTURE. As far as slides are four factors condition the feasibility of stabilization projects. First the of the active sliding mass imposes limits to any type of resilient infrastructure arid is of major criteria to select the appropriate system (for instance length of anchors, depth of drainage boreholes or trenches, etc.). Thus many landslide zones in Switzerland as as in the world cannot be stabilized due to the large depth of the sliding niass, exceeding 100 Then the of slide, mainly its average permanent movement, determines the possibility of application of some construction techniques, specially when the major displacements are at a unique slip surface. For example, vertical drainage boreholes are only when the movement is slow enough (approx. 1 to allow effect to they are sheared. A third important point is the occurrence of some lateral zones of a slide or at the limits of a secondary slip surface which induce unhomogeneous conditions in of depth, velocity, movement pattern, so that the buildings and these zones can be severely affected. These first three factors are somehow related to the general notion of intensity in a analysis. The last factor rather deals with the concept of which has to also considered in a hazard and risk analysis. It includes the potential for progressive or sudden accelerations which often cause distress to supposedly resilient infrastructure. Such accelerations depend mainly on the variations of climatic conditions, either at a scale (high intensity during some days to some months) or at a scale (periods of several wet years, global climate change). The effects of an increase of precipitations can be either direct, raising the groundwater level and inducing higher forces in sliding mass, or indirect, for example through more significant erosion rate at the toe of the slide. Such a relation is quite often complex and needs long-term monitoring to assess this parameter. As far as are concerned, the last factor mentioned above is certainly prevailing, as high intensity are the main cause of disaster. In this case the major difficulty lies in the determination of local precipitation distribution as intense rainfall on limited drainage area may not recorded at the nearby raingauge station. A second factor for assessing the intensity of the event is the of the stream in which it occurs, as it will directly condition the velocity of the debris flow, and thus the potential for increasing the by final factor is availability in the upper ...
