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Noninvasive techniques for site characterization of Alberta seismic stations based on shear-wave velocity

Joseph J. Farrugia, Sheri Molnar and Gail M. Atkinson
Noninvasive techniques for site characterization of Alberta seismic stations based on shear-wave velocity
Bulletin of the Seismological Society of America (December 2017) 107 (6): 2885-2902

Abstract

We collected site-specific geophysical data at 28 seismic stations on various soils in Alberta, Canada. Noninvasive seismic procedures are combined with the earthquake database and other available regional data sets to improve current understanding of earthquake site effects at the stations. Such an understanding allows the separation of site effects from source and path effects, which is important for ground-motion modeling. Dispersion data sets were compiled using multichannel analysis of surface waves and ambient vibration array field methods. We also computed microtremor horizontal-to-vertical spectral ratios using three-component single-station measurements. Independent and joint inversion of these two data sets allowed us to characterize 18 seismic stations in terms of shear-wave velocity-depth profiles. We report the range in the time-weighted average shear-wave velocity in the upper 30 m (VS30) derived from average shear-wave velocity-depth profiles for each site and their corresponding National Building Code of Canada (NBCC) site classification. Corresponding time-averaged velocity values are also computed for the top 5, 10, and 15 m. The parameter that is best constrained is VS15, which is related to relatively thin (<30 m) sedimentary overburden in Alberta. In general, Alberta seismic stations are typically characterized by regolith <30 m thick with low shear-wave velocity (< or =200 m/s), underlain by material with a higher shear-wave velocity (>400 m/s). NBCC site classes are limited to C and D for the sites we surveyed, with D being the predominant site class.


ISSN: 0037-1106
EISSN: 1943-3573
Coden: BSSAAP
Serial Title: Bulletin of the Seismological Society of America
Serial Volume: 107
Serial Issue: 6
Title: Noninvasive techniques for site characterization of Alberta seismic stations based on shear-wave velocity
Affiliation: Western University, Department of Earth Sciences, London, ON, Canada
Pages: 2885-2902
Published: 201712
Text Language: English
Publisher: Seismological Society of America, Berkeley, CA, United States
References: 52
Accession Number: 2018-031667
Categories: SeismologyEngineering geology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 5 tables, sketch map
N51°00'00" - N56°00'00", W116°00'00" - W111°00'00"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute. Abstract, Copyright, Seismological Society of America. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 2018
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