Seismic loss estimates for buildings in Bucharest's historic centre in case of another 1977 Vrancea earthquake

Abstract

As past seismic events showed, Bucharest (capital of Romania) can be significantly affected by another intermediate depth (or subcrustal) Vrancea earthquake. The 1940 (Mw 7.7) and 1977 (Mw 7.4) earthquakes put the number of casualties in Bucharest over 1600. Although most people and authorities are aware of the exposure, the mitigation actions are still improper and there is actually a very uncertain image of the current damage extent. The paper provides scientifically based answers, through quantitative earthquake loss estimation based on recently developed analytical methods, applied for buildings in the historic centre of Bucharest. The approach offers a relevant picture of the actual possible damage distribution after an earthquake similar to the 1977 event, in an area with heavy traffic and a high number of tourists. The Improved Displacement Coefficient Method used in this study relies on the description of structural behaviour within different limits due to specific ground motion parameters like spectral acceleration. The 358 buildings in the study area are assessed individually and specific vulnerability curves are assigned to each typology, based on height, construction year and material. The same classification as in the Near Real-Time System for Estimating the Seismic Damage in Romania is used. The results are evaluated in order to be further included in the system. In addition, an empirical loss assessment procedure reflecting the economic impact of the previously calculated situation was employed. Relevant maps for mean damage ratio and economic losses are presented and interpreted.