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<br />0028D2 <br /> <br />Terrain Analysis Maps <br /> <br />These maps are based on the principle that landforms such as rockfalls, debris <br />flows, and slumps are produced by various identifiable natural processes, such <br />as landsliding, downslope creep, and erosion. A terrain map distinguishes <br />"terrain units" which are various kinds of topography that are undergoing the <br />same set of processes. These maps are mainly used for regional <br />reconnaissance. Since they do not specifically label landslides and debris <br />flows, they require further interpretation and development before they can be <br />used. <br /> <br />Landslide Hazard Maps <br /> <br />These maps show the areal extent of any threatening process; where landslide <br />processes have occurred in the past, where they occur now, and the probability <br />that a landslide will occur in the future. They contain detailed information <br />on the type of landslide, extent of slope subject to failure, probable maximum <br />extent of ground movement, and the probable frequency of failure. <br /> <br />These maps can be used to predict the relative degree" of hazard in the <br />landslide area. <br /> <br />Landslide Risk Map <br /> <br />This kind of map would indicate the area and/or population that is exposed to <br />landslide hazard, the vulnerability of the area and/or population to the <br />landslide, and the expected consequences to people and structures if a <br />landslide occurs (Brabb, 19B4). <br /> <br />Evaluation of the risk requires a knowledge of the structures or lives that <br />can be affected by a given hazard in combination with knowledge of the hazard <br />itself. Some European countries use a simple three zone system: 1) a zone of <br />unacceptable risk, 2) a zone of "balanced" risk (requiring safety features <br />such as dams, channel revetments etc.), and 3) a zone of acceptable risk. <br />What constitutes an acceptable or unacceptable risk has to be determined in a <br />given context or situation. Greater risk may be acceptable or more costly <br />mitigation feasible in areas where land is scarce and valuable. Also, the <br /> <br />- 16 - <br />