Windstorms, the most costly natural hazard in Europe

Windstorms cause more than half of the economic loss associated with natural disasters in Europe (Munich Re, 1999; 2007). Their comparatively high frequency in combination with the enormous concentration of values in Europe results in a loss potential only comparable with earthquakes and hurricanes in the United States and Japan. Consequently, there is a high awareness of these risks in European countries. The institutions involved in the warning and rescue processes, like weather services, fire brigades and regional governments, have developed methodologies along the applicable regulations, which are country specific. Risk map zones have been developed and have been incorporated in official building regulations (e.g. DIN 1055–4 in Germany). Insurance against the monetary loss arising from the direct effects of windstorms is not compulsory in all countries. Still, such insurance is commonly contracted. With respect to residential buildings, for example, there is a typical insurance density of about 90 per cent (Bresch et al., 2000). The cumulative effects of storm damage could endanger insurance company solvency, which is again subject to national and international regulations (Solvency II). Part of the required knowledge of windstorm risks is based on proprietary risk models, available to insurance brokers on a commercial basis from companies specialised in these services. Large-scale windstorm events can be identified either from the damage they produce or from meteorological data. Of course, the representation of a windstorm in terms of meteorological data and damage data may be quite different. A top storm in meteorological terms is not always a top storm in terms of damage (and vice versa), as significant damage sums only occur when high winds hit a highly populated area. Such effects must be taken into account, in particular when attempting to use meteorological data for assessments of related damage.