Extending urban seismic risk assessment to open spaces for the 2011 Lorca earthquake scenario

We extend the conventional seismic risk assessment approach to open spaces in the 2011 Lorca earthquake scenario. Conventional approaches to seismic risk provide estimates of damaged buildings mainly related to structural failure. The damage related to the production of debris in damaged buildings and its spread in the surrounding space receives a secondary role. However, in many cases, this secondary damage is of prime importance. In this work, we consider the Mw5.2, 2011 Lorca earthquake (Spain), which caused nine fatalities associated with the fall of non-structural building parts. First, we analyze reports of emergency interventions, including those related to debris removal, and we derive their geographical and temporal distributions. Then, we introduce an extension of the conventional risk model to include the debris generated in damaged buildings and its accumulation in open spaces. We apply this risk extension model together with the conventional risk model to estimate the distributions of damaged buildings and of debris volumes related to the 2011 Lorca earthquake scenario. Results indicate differences between predicted and observed damage estimates within a half-damage degree interval and differences in debris volumes within the same order of magnitude. The approach presented is easily exportable to urban risk studies of other areas.