Analyzing the effect of anisotropic spatial correlations of earthquake intensity measures on the result of seismic risk and resilience assessment of the portfolio of buildings and infrastructure systems

The seismic risk assessment of spatially distributed assets requires a seismic hazard that considers the spatial correlations of earthquake intensity measures (IMs). Several spatial correlation models have been developed to address this concern, but the majority of existing models are based on the hypothesis of isotropy. Recent investigations revealed that the assumption of isotropy is not generally valid, and the anisotropy condition should be taken into account when considering the spatial correlations of earthquake IMs. On the other hand, it is necessary to investigate the significance of the inclusion of anisotropy in seismic risk and resiliency assessment. The main objective of the current study is to address this issue using three different spatial correlation models. Two of them are based on the linear model of coregionalization method, which describes the spatial correlation of earthquake IMs from the isotropy point of view. The third model is based on the latent dimensions method, which can take the anisotropy into account. The results of the current study reveal that the ignorance of anisotropy of spatial correlations of earthquake IMs causes unrealistic loss estimation and leads to inaccurate resilience assessment of spatially distributed assets and systems. It is demonstrated specifically that the isotropic models generally overestimate the infrequent loss values which is on the safe side, but underestimate the frequent loss values that is non-conservative.