Seismic vulnerability and damage assessment in Navarre (NE Spain)

A regional characterization of the seismic vulnerability of the building stock of Navarre (Northern Spain) and the expected damage associated with expected ground shaking for a 475-year return period is presented. Besides the initial planning meetings, the work consists on three phases: The first is the field work conducted along different routes crossing the entire region, including main cities. Two geographical areas with distinctive construction patterns and characteristic typologies were recognised and delimited, together with a transition zone. Several buildings were sampled and documented, and empirical vulnerability distributions were obtained. The second phase relates to cadastral data exploitation and processing, selection of parcels as working units and selection of municipalities and districts as representation units. Based on the age of construction and the associated seismic code requirements; the number of stories; and the empirical distributions derived in the earlier stage, statistical distributions of building vulnerability classes were composed following three vulnerability classifications. These include the vulnerability classification of the European Macroseismic Scale, the vulnerability index approach and the Hazus classification. This phase was as important as time-consuming, and set the basis for the proper development of the subsequent analyses. The third phase consisted on calculating the expected damage with empirical as well as with analytical methods, using as seismic input an updated hazard-consistent seismic intensity map of the region. Vulnerability and damage results derived with the three methods used are compared and analysed, and their suitability discussed. Results of this work will be used in the regional seismic risk plan of Navarre (RISNA Project)