Development of regional site amplification models for eastern canada

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The location of Montreal and Ottawa in the active Western Quebec seismic zone places them at risk of seismic hazards. The potential risk was recently highlighted with the magnitude M5.0 earthquake on June 23, 2010, located about 50 km northeast of the city of Ottawa. This earthquake was felt strongly in areas of Ottawa that are located on soft postglacial sediments, which amplified the level of earthquake shaking. Soil amplification can significantly influence the ground motions and hazards of seismic events; and, the most recent version of the National Building Code of Canada (2005) recognizes its importance with a seismic site classification system to determine soil amplification factors. The results of past pilot research indicate that the seismic soil amplification factors given by the National Building Code of Canada, which are mainly based on the Californian database, are not adequate for Eastern Canada, due to the unique geological and geotechnical conditions of postglacial sediments in the region. Earthquake recordings in the Ottawa region show that the soil amplification is large relative to the typical amplification factors being used in geotechnical practice. The proposed interdisciplinary research will provide a unique region-specific model of seismic soil amplification for different site classes in Eastern Canada. The research will be linked with complementary efforts by the Canadian Seismic Research Network (CSRN). CSRN has emphasized that the development of region-specific seismic soil amplification factors is an important element for the reduction of urban seismic risk in Canada. Results of the proposed research will lead to an improved understanding of soil amplification behaviour to strong seismic motions; and, the long-term plan is the provision of region-specific seismic soil amplification factors for Eastern Canada, which will be influential in guiding improvements for future versions of the National Building Code of Canada and for site-specific studies.