Deaggregation of seismic loss of spatially distributed buildings

The catastrophic nature of seismic risk resides in the fact that a group of structures and infrastructure is simultaneously excited by spatially correlated seismic loads due to an earthquake. For this, both earthquake-to-earthquake (inter-event) and site-to-site (intra-event) correlations associated with ground motion prediction equations must be taken into account in assessing seismic hazard and risk at multiple sites. The consideration of spatial correlation of seismic demand affects aggregate seismic losses as well as identified scenario seismic events. To investigate such effects quantitatively, a simulation-based seismic risk model for spatially distributed structures is employed. Analysis results indicate that adequate treatment of spatial correlation of seismic demand is essential and the probability distribution of aggregate seismic loss can be significantly different from those based on the assumptions that seismic excitations are not correlated or fully correlated. Furthermore, the results suggest that identified scenario events by deaggregation in terms of magnitude and distance become more extreme if the spatial correlation is ignored.