Comparative Seismic Risk Studies for German Earthquake Regions Damage and Loss Assessment for the City of Cologne

In current research quantifying loss potentials for German city regions basic tools for GIS-based seismic risk assessment technologies have been developed and applied to the building stock and regional particularities of German earthquake regions. Different study areas with comparable levels of seismic hazards were investigated, but they had varying numbers of inhabitants and degrees of urbanization. This paper focuses on the case study of Cologne as an example for a larger city, and is related to results of the German Research Network Natural Disasters DFNK-project [1]. Seismic risk maps were prepared for different EMSintensities. The impact of model assumptions and the step-wise refinement of input variables on the distribution of expected building damage are recognized as leading to different risk maps. Furthermore, the zones of higher risk are identified. An integrated approach combining data from official and insurance statistics was used to develop an inventory of exposed values in Cologne. A loss estimation procedure was applied converting results of refined vulnerability and damage assignments into mean damage ratios for the 370 municipalities. Results are available for different scenario events (with return periods TR between 475 and 10.000 years). Results support the prognosis that in the case of strong earthquakes the loss might rise to maximum values between 25 and 30 billion US $ for the city, and up to 60 billion US $ (and still higher) if all whole surrounded regions are considered. This estimate is consistent with previous lower bound estimates by Allmann et al. [2]. The extent to which extent the loss varies due to scenario event, local site effects, the vulnerability of building types, the assigned asset, and the implied correlation between damage and loss is also shown.