| Titre | Soft soil response investigations in Kitimat, BC - some preliminary results |
| Auteur | Crow, H L; Hunter, J; Brewer, K; Brillon, C; Cote, M; Allen, T; Cassidy, J F; Hayek, S |
| Source | Proceedings of the 11th Canadian Conference on Earthquake Engineering (11th CCEE); par Canadian Association for Earthquake Engineering; Earthquake Engineering and Engineering Vibration 2015, 9
pages |
| Liens | Online - En ligne
(ResearchGate)
|
| Année | 2015 |
| Séries alt. | Secteur des sciences de la Terre, Contribution externe 20150034 |
| Réunion | 11th Canadian Conference on Earthquake Engineering (CCEE); Victoria; CA; juillet 21-24, 2015 |
| Document | publication en série |
| Lang. | anglais |
| Media | papier |
| Formats | doc |
| Province | Colombie-Britannique |
| SNRC | 103I/02 |
| Lat/Long OENS | -128.7500 -128.5000 54.0833 54.0000 |
| Sujets | études pédologiques; interpretations sismiques; dépôts glaciaires; levés sismiques; secousses séismiques; dépôts fluviaux; sédiments marins; pédologie; géophysique |
| Illustrations | location maps; seismic maps; seismic velocity profiles; seismic profiles; tables; graphs |
| Programme | Cartographie et Surveillance-Risques Géologique Marine (CSGM), Tremblements de terre |
| Résumé | (disponible en anglais seulement)
The north coast town of Kitimat, BC is located in a zone of moderate seismic hazard, relative to high-hazard regions of southwest BC. The town is underlain by
a valley filled with unlithified glacial, soft fluvial, and marine sediments deposited on firm bedrock. Such settings are commonly prone to earthquake ground motion amplification and resonance effects. Reconnaissance field surveys were conducted to
measure resonance effects in areas of thick soft soil. Results indicate substantial Horizontal-to-Vertical Spectral Ratio (HVSR) peaks at frequencies as low as 0.41 Hz using a portable seismograph. During these surveys, a local MW 4.6 earthquake
occurred to the west of Haida Gwaii (275 km away) and was recorded by both the portable seismograph at a soft soil site and at a bedrock site 2.5 km away. Comparisons of the time histories showed considerable amplitude and frequency differences
between the soil and rock sites. At the soil site, an HVSR resonant peak amplitude of 8 was recorded at 0.84 Hz during ambient noise measurements, whereas an HVSR peak amplitude of 21 was observed from the surface-wave portion of the earthquake
event. Particle-motion plots of various portions of the earthquake time series at the soil site showed several packets of late arriving "valley-generated" surface waves at the site resonance frequency which were not observed at the rock site. These
preliminary results demonstrate the importance of conducting additional site response investigations in this region. |
| Résumé | (Résumé en langage clair et simple, non publié et disponible en anglais seulement)
The north coast town of Kitimat, British Columbia, is located in a zone of moderate seismic hazard. The town
is underlain by a valley filled with unconsolidated glacial, soft fluvial, and marine sediments deposited on firm bedrock. Such settings are commonly prone to earthquake ground motion amplification and resonance effects. Field surveys were conducted
to measure resonance effects in areas of thick soft soil. Results indicate substantial Horizontal-to-Vertical Spectral Ratio (HVSR) peaks at frequencies as low as 0.41 Hz using a portable seismograph. During these surveys, a local Mw4.6 earthquake
occurred offshore Haida Gwaii (275 km west) and was recorded by both the portable seismograph at a soft soil site and at a bedrock site 2.5 km away. Comparisons of the time histories showed considerable amplitude and frequency differences between
soil and rock. |
| GEOSCAN ID | 296374 |
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