| Title | Seismic microzonation of a region with complex surficial geology based on different site classification approaches |
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| Author | Salsabili, M; Saeidi, A; Rouleau, A; Nastev, M |
| Source | Geoenvironmental Disasters vol. 8, issue 1, 27, 2021 p. 1-13, https://doi.org/10.1186/s40677-021-00198-8  Open Access |
| Image |  |
| Year | 2021 |
| Alt Series | Natural Resources Canada, Contribution Series 20210536 |
| Publisher | Springer Science and Business Media Deutschland GmbH |
| Document | serial |
| Lang. | English |
| Media | paper; on-line; digital |
| File format | pdf; html |
| Province | Quebec |
| Area | Saguenay; Canada |
| Lat/Long WENS | -71.6264 -70.5161 48.5772 48.1850 |
| Subjects | Science and Technology; seismology |
| Illustrations | location maps; 3-D models; tables; graphs; cross-sections; cross-plots |
| Program | Public Safety
Geoscience Rapid Risk Assessment |
| Released | 2021 10 11 |
| Abstract | A seismic microzonation study was conducted to refine the seismic hazard model for the city of Saguenay, Canada. The Quaternary geology underlying Saguenay shows complex glacial and post-glacial
stratigraphy with a number of buried valleys filled with fluvioglacial and glaciomarine sediments. High impedance contrast between rock formations and surficial sediments is prone to seismic amplification. To evaluate their applicability, advantages
and limitations in capturing the geological specificity of the study area, four site classification methods were applied: the current National Building Code of Canada (NBCC) and Eurocode 8, both mainly based on the average shear-wave velocity for the
surficial sediments (VS,avg) and for the top 30 m (VS,30); a method based on the fundamental site period (T0); and a hybrid method based on the combination of VS,30, T0 and VS,avg. The study specifically aimed to evaluate the importance of the site
classification parameters on the resulting microzonation maps. VS,30 is capable to present the geological and geotechnical site conditions, however, the results may be further improved by considering Vs,avg in shallow and T0 in thick layers of soil
sediments as secondary parameters. The T0 method gives also satisfactory results with T0 showing a better correlation to Vs,30 than to Vs,avg. The versatile hybrid method may be challenging to apply in certain cases with its nine different site
categories and parameters. |
| Summary | (Plain Language Summary, not published)
The objective of the present study is to quantify the potential impacts of the local geological and geotechnical settings on the duration and the
amplitude and frequency content of the incoming seismic waves in the Saguenay region, Canada. These impacts are often referred to as 'site effects'. The recent geology in the study area is characterized with complex glacial and post-glacial
sediments. These unconsolidated sediments of relatively low stiffness overlie the solid bedrock formations of the Canadian schield. The high contrast in the stifness properties may contribute to the amplification of the intensity of seismic shaking
during a strong earthquake event. Four site classification methods were applied to evaluate their advantages and limitations in capturing the geological specificity of the study area: the current National Building Code of Canada (NBCC) and Eurocode
8, both mainly based on the average shear-wave velocity (Vs) as a measure of the stifness of the surficial geological units; a method based on the fundamental vibration period of the surficial sediments (To); and a hybrid method based on the
combination of Vs and To. The results indicate that Vs and To based nethods are efficient in evaluating the local geological and geotechnical conditions. Further improvement were achieved considering Vs in shallow and To in thick layers of soil
sediments as secondary parameters. The hybrid method revealed as the most sophisticated with nine different site categories and sets of parameters, but may be challenging to apply. |
| GEOSCAN ID | 329429 |
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