Characterization of site effects in Montreal, Canada

Recent destructive earthquakes have clearly shown that near-surface geological conditions play a major role in the level of ground shaking in urban areas. In Canada, Montreal is ranked second for seismic risk after Vancouver considering its population and regional seismic hazard. The city is largely...

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Bibliographic Details
Published in:Natural hazards (Dordrecht) 2009-02, Vol.48 (2), p.295-308
Main Authors: Rosset, P., Chouinard, L. E.
Format: Article
Language:English
Subjects:
Civil Engineering
Earth and Environmental Science
Earth Sciences
Earth, ocean, space
Earthquakes
Earthquakes, seismology
Emergency preparedness
Engineering and environment geology. Geothermics
Environmental Management
Exact sciences and technology
Geophysics/Geodesy
Geotechnical Engineering & Applied Earth Sciences
Hydrogeology
Internal geophysics
Land use
Natural Hazards
Natural hazards: prediction, damages, etc
Original Paper
Public safety
Risk assessment
Seismology
Urban planning
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Summary:Recent destructive earthquakes have clearly shown that near-surface geological conditions play a major role in the level of ground shaking in urban areas. In Canada, Montreal is ranked second for seismic risk after Vancouver considering its population and regional seismic hazard. The city is largely built on recent unconsolidated marine and river deposits and most of its infrastructure is old and deteriorated. A seismic risk project that includes a combined methodology for site effects zoning in large cities, using microtremor measurements ( H / V method) coupled with 1D numerical modelling (SHAKE91), has been initiated. The experimental approach gives good estimates of the fundamental frequency of soft deposits, while the numerical approach provides good estimates of the soil response in terms of amplification factor related to frequency. Main mechanical properties of soft soils were compiled from various data available, and a sample of input rock motions from real and synthetic earthquakes was used to compute soil response. The influence of marine clays on soil response is significant and is well correlated with thickness of these deposits. PGA amplification factors range from 2 to 4 at frequencies from 2 to 7 Hz, with some occasional larger values. The results demonstrate that the methodology used for our study is both fast and efficient to determine the influence of soft soils in urban environments. Such studies are essential for the effective deployment of seismic instrumentation, land-use planning and seismic mitigation.
ISSN:0921-030X
1573-0840
DOI:10.1007/s11069-008-9263-1