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TitleRegional Vs30 model for the St. Lawrence Lowlands, eastern Canada
AuthorNastev, M N; Parent, M P; Benoit, N B; Ross, M R; Howlett, D
SourceGeorisk vol. 10, issue 3, 2016 p. 200-212
Alt SeriesEarth Sciences Sector, Contribution Series 20140211
PublisherTaylor & Francis
Mediapaper; on-line; digital
File formatpdf
ProvinceQuebec; Ontario
NTS31G; 31H; 31I; 21L; 21G
AreaSt. Lawrence Lowlands
Lat/Long WENS -76.0000 -70.0000 47.0000 45.0000
Subjectsgeophysics; s waves; seismic waves; modelling; seismic velocities; marine sediments; Vs30 model; seismic site response; 3D geology
Illustrationslocation maps; 3-D models; graphs; plots; histograms
ProgramQuantitative risk assessment project, Public Safety Geoscience
AbstractShear-wave velocity of the top 30 m, VS30, is commonly used for prediction of the seismic site response. This paper presents development, validation and uncertainty assessment of a regional VS30 model based on a combination of simplified 3D geology and statistically representative velocity values. Results identify soft marine sediments in deep sedimentary basins as zones most
susceptible to seismic shaking. Compared to the available urban-scale seismic zonation studies, the regional model showed a success rate of roughly 64% in predicting local site category. The standard deviation was in average 30% of the expected VS30 value.
Summary(Plain Language Summary, not published)
Three regional methods for mapping of the shear wave velocity (geophysical parameter related to the soil stiffness) of the top 30 m were applied using different proxies: surficial geology, topographic slope, and simplified 3D geologic modelling. Available geophysical data were combined to improve the accuracy. The final seismic zonation maps were generated with resolution of 500 m and compared with existing detailed urban-scale studies. The validation process showed that the 3D geologic modelling method in combination with representative shear wave velocity values was by far superior in predicting the seismic site conditions. The success rate was about 70%, and in 95% of cases within ±1 soil class range.