Sensitivity Analysis of Ordered Weighted Averaging Operator in Earthquake Vulnerability Assessment

The main objective of this research is to find the extent to which the minimal variability Ordered Weighted Averaging (OWA) model of seismic vulnerability assessment is sensitive to variation of optimism degree. There are a variety of models proposed for seismic vulnerability assessment. In order to examine the efficiency of seismic vulnerability assessment models, the stability of results could be analysed. Seismic vulnerability assessment is done to estimate the probable losses in the future earthquake. Multi-Criteria Decision Making (MCDM) methods have been applied by a number of researchers to estimate the human, physical and financial losses in urban areas. The study area of this research is Tehran Metropolitan Area (TMA) which has more than eight million inhabitants. In addition, this paper assumes that North Tehran Fault (NTF) is activated and caused an earthquake in TMA. 1996 census data is used to extract the attribute values for six effective criteria in seismic vulnerability assessment. The results demonstrate that minimal variability OWA model of Seismic Loss Estimation (SLE) is more stable where the aggregated seismic vulnerability degree has a lower value. Moreover, minimal variability OWA is very sensitive to optimism degree in northern areas of Tehran. A number of statistical units in southern areas of the city also indicate considerable sensitivity to optimism degree due to numerous non-standard buildings. In addition, the change of seismic vulnerability degree caused by variation of optimism degree does not exceed 25% of the original value which means that the overall accuracy of the model is acceptable.