Seismic risk scenarios in a cross-border zone of the Pyrenees Pyrenees

Abstract : Within the frame of the SISPYR project (Seismic Information System for the Pyrenees, 2009-2011), a seismic risk evaluation of seismic risk is presented for a cross-border zone in the Pyrenees (Saint-Beat and Luchon in France and the Val d'Aran in Spain) is presented. This area has been selected because of recent seismic activity and the importance of tourism in this region. The vulnerability of existing buildings is assessed by using the vulnerability indices proposed by the RISK-UE project. This method is based in vulnerability classes defined by the EMS-98 intensity scale. Semi-empirical functions transform vulnerabilities into physical damage distributions as a function of seismic intensity. The most representative building typologies of current buildings in the area have been identified as well as their distributions within the zone. Some essential buildings have also been considered in the scenario. This information has been integrated into a GIS. The deterministic scenario considered is based on the observed and interpreted intensities of Vielha 1923 earthquake (maximal observed intensity VIII). Another scenario, based on the probabilistic seismic hazard for a return period of 475 years, is calculated taking into account the soil amplification map in for the valleys obtained from the site effects study carried out within the project. The probabilities of occurrence of direct physical damage to buildings could be used to estimate human casualties and economic losses. These results will be useful for defining prevention strategies and civil protection.