Abstract

The Greater Vancouver Regional District (GVRD) is exposed to some of the highest levels of seismic risk in Canada, and for the dense urban infrastructure and populations of the downtown Vancouver core; it poses an even higher risk.  For risk management and emergency planning in a major earthquake scenario, it is essential to evaluate the structural damage to buildings and the resulting loss estimation. For this analysis, a building inventory of Vancouver’s downtown core with a classification scheme of 31 prototypes was supplied by the Department of Civil Engineering at the University of British Columbia.  The basis of our analysis is to estimate the structural and non-structural damage to buildings in Vancouver and the resulting monetary losses and casualties for different levels of ground shaking intensities.  In order to relate the expected level of damage for each prototype with different levels of ground shaking, damage probability matrices (DPM’s) were used.  DPM’s are Modified Mercalli Intensity (MMI) based relationships and are central to the analysis.

This paper has three main sections. The first considers the development of a relational geodatabase using Microsoft Access in order to estimate the many possible outcomes of different earthquake scenarios. Once the database was developed, we were able to estimate the amount of structural and non-structural damage, monetary losses, and casualties expected for each building within the study area for different intensity events, MMI VI - XII. The database also provides a report for each building in the database. We also used these results to produce maps showing the spatial distribution on a per block basis using the Geographic Information System (GIS) software, ArcMap 9.2.

The second section explains the methodology involved in the evaluation of structural and non-structural damage as well as monetary loss estimation. For MMI events VI - XII, the probability and amount of structural and non-structural building damage was calculated using the DPM’s for the BC 31 classification. The third section follows a methodology for casualty estimation. Casualty estimates per building were calculated for MMI VI - XII. This section presents an adjusted methodology for Southwestern British Columbia casualty estimates developed by following the Californian method created by HazUS. Data used in this method comes from Canadian census variables, the building inventory, damage probability matrices, and HazUS casualty rates. These casualty rates were defined by building prototype and were converted to casualty rates for the 31 prototypes in Southwestern B.C. The results were determined for three different times of the day (2a.m., 2p.m., and 5p.m.). This model also predicts the number of injuries expected both indoors and outdoors of a building. The results contain predicted numbers of injuries and casualties for 4 severity levels, describing slight, serious, life threatening and fatal injuries.