Empirical vulnerability curves for Icelandic low-rise buildings based on zero-inflated beta regression model

Abstract

In June 2000, two earthquakes of ~Mw6.5 struck in South Iceland, and in May 2008 the same region was hit again further west, with Mw6.3 event. Almost 5000 residential buildings were affected in each of these two seismic events. To fulfil insurance claims, detailed, and complete loss data were collected in each case, and the 2000 dataset and 2008 dataset were established. Having access to two high quality loss datasets from different size earthquakes, affecting the same building typologies in the same region, is rare to find in the literature. An advanced empirical vulnerability model based on zero-inflated beta regression was fitted to five building typologies, classified according to the GEM taxonomy system, independently for the 2000 dataset and the 2008 dataset. Status of seismic codes was considered when defining the building typologies. PGA was used as intensity measure. For all the five building typologies, the calibrated vulnerability functions and the fragility curves are substantially different from these two datasets. This indicates that PGA is not alone an adequate intensity measure to predict losses. The results also show that status of seismic code affects the performance of the buildings as one would like to see.