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This paper presents a comparison of the two main regional damage estimation methodologies currently in use, namely the modified Mercalli intensity (MMI) based approach and the spectral parameter based approach. In the first methodology, expected damage is related to ground shaking intensity in terms of MMI through damage probability matrices. In the second methodology, the ground motion intensity is described in terms of spectral acceleration (SA), and building response in terms of spectral displacement (SD). Both methodologies were applied to buildings in Vancouver of three different construction types: single-family wood-frame houses, low-rise unreinforced masonry buildings, and high-rise concrete frame structures with concrete shear walls. The two methodologies predict damage that lies in the same general damage categories of light and moderate, which are defined by fairly broad ranges in mean damage factors. The specific mean damage factors predicted by the two methods for a given location are significantly different, however. The significant differences in mean damage factors imply significant differences in damage costs and hence in seismic risk. [ABSTRACT FROM AUTHOR]

This paper presents the results of regional seismic risk assessment studies that were carried out for two cities in southwestern British Columbia, Vancouver and Victoria. Ground shaking intensity in the area was obtained using the seismic source zones delineated by the Geological Survey of Canada for a probability level of 10% chance of exceedance in 50 years. Building inventories were compiled by aggregating data from sidewalk surveys as well as municipal databases. Modified Mercalli intensity-based damage matrices that relate the level of ground shaking to the amount of damage expected in different types of structures were used to estimate damage to structural and non-structural components of buildings. Estimated damage and loss distributions were mapped on a block-by-block basis. The historic sections of the cities were estimated to have damage levels between 10% and 30% of the replacement cost, while in the rest of the cities the estimated damage was generally in the 5% to 10% range. The results show the estimated economic loss distribution is considerably different from the damage distribution. Although the older neighbourhoods of the cities are expected to suffer highest amount of damage, the highest amount of economic loss is estimated to occur in areas with concentration of concrete high-rise buildings. [ABSTRACT FROM AUTHOR]