Geomorphic Hazards and Natural Risks
Western European countries are subject to natural phenomena that can cause disasters. Their origins are various: geophysical (earthquakes), hydrometeorological (sea storms, floods, and avalanches), or geomorphologic (landslides). They are fairly widespread but less frequent and of relatively low intensity compared with other regions of the world; for example, an earthquake in France or Belgium is not likely to be as violent as in Greece or Japan. Some of the countries concerned, such as France and Germany, are subject to all the hazards mentioned above, while Denmark and The Netherlands are seldom exposed to earthquakes and never to avalanches because they have no mountains. Man is not responsible for phenomena such as earthquakes, but contributes significantly to the onset and aggravation of other hazards, and is sometimes largely responsible for the direct and indirect consequences, having built and maintained installations in ‘risk’ sectors. The number of victims and the cost of the damage may be high, depending on the circumstances, the intensity, and the duration of the phenomenon. Western European countries have experienced real natural disasters in the distant or recent past. Floods following a storm wave in The Netherlands in 1953 were responsible for some 2,000 deaths and damage amounting to over 3 billion Euros. Two hundred people died in the most destructive flood ever known in France in 1930 in the Tarn (Ledoux 1995). Natural phenomena such as these can recur with at least the same intensity but may entail much greater damage because of increased human occupation in the sectors concerned: the flooding submerges zones which are much more urbanized than they were in the nineteenth century. Whether prevention measures are taken depends on the level of risk which the populations concerned are prepared to accept. These measures should be associated with spatial and temporal forecasts and preceded by an analysis of the processes for these phenomena to be fully understood. In order to remove the ambiguities and the inaccuracies of terminology that are observed all too often, it is necessary in the first instance to define ‘geomorphic hazards and natural risks’, particularly in terms of the notions of risk, hazards, and vulnerability.