Spatial multi-criteria risk assessment of earthquakes from Bucharest, Romania

Abstract

The current paper is a piece of exploratory research, having as its purpose the evaluation of seismic risk spatial patterns for Bucharest, the capital of Romania. In this paper, risk (expressed in terms of risk indices) is calculated as a combination of hazard and vulnerability information, based on the semi-quantitative technique of multi-criteria spatial analysis. The scale of analysis was considered at the level of the census units (2002). The hazard component consists of the probability of occurrence of two scenarios: (1) an occurred earthquake that is a typical hazard case for the Vrancea region (event of 30 August 1986, Mw =7.1) and (2) a computed seismic hazard for the largest magnitude earthquake expected to be generated in Vrancea (Mw =7.7). In both cases, the seismic hazard is expressed in terms of peak ground acceleration (PGA) values. The total vulnerability index is obtained using four groups of indicators: natural environment, physical, social and economical indicators. The overall vulnerability to seismic hazard is assessed by comparing total vulnerability with the compound capacity factor. The resulting risk indices are relative, expressed by numerical values, ranging between 0 and 1, that do not have a direct meaning of expected losses. The spatial pattern of risk shows a significant increase in the case of the maximum expected event as compared with the 1986 earthquake case, particularly in the central part of the city. As a general conclusion, only the strongest earthquakes are really dangerous for Bucharest.