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TitleSeismic site characterization with shear wave (SH) reflection and refraction methods
AuthorHunter, J A; Crow, H LORCID logo; Stephenson, W J; Pugin, A J -M; Williams, R A; Harris, J B; Odum, J K; Woolery, E W
SourceJournal of Seismology 2022 p. 1-22, Open Access logo Open Access
Alt SeriesNatural Resources Canada, Contribution Series 20200677
Mediapaper; on-line; digital
File formatpdf; html
ProvinceBritish Columbia
AreaSan Fernando Valley; United States of America; Canada
Lat/Long WENS-118.7500 -118.2500 34.3500 34.0000
Lat/Long WENS-123.2978 -122.8883 49.2536 48.9678
SubjectsScience and Technology
Illustrationsdiagrams; photographs; charts; tables; location maps
ProgramPublic Safety Geoscience Intraplate Earthquakes
Released2022 01 01
AbstractReflection and critically refracted seismic methods use traveltime measurements of body waves propagating between a source and a series of receivers on the ground surface to calculate subsurface velocities. Body wave energy is refracted or reflected at boundaries where there is a change in seismic impedance, defined as the product of material density and seismic velocity. This article provides practical guidance on the use of horizontally propagating shear wave (SH-wave) refraction and reflection methods to determine shear wave velocity as a function of depth for near-surface seismic site characterizations. Method principles and the current state of engineering practice are reviewed, along with discussions of limitations and uncertainty assessments. Typical data collection procedures are described using basic survey equipment, along with information on more advanced applications and emerging technologies. Eight case studies provide examples of the techniques in real-world seismic site characterizations performed in a variety of geological settings.
Summary(Plain Language Summary, not published)
The near-surface geological conditions at a site can have a significant impact on the amplitude and duration of seismic waves as they reach the surface. To reduce the effects of significant ground motion on structures, modern building codes worldwide have adopted seismic site classification schemes with categories which can be defined by the time-averaged shear (S) wave velocity to a specified depth (typically 30 m, referred to as Vs30). While many methods (direct and indirect, invasive and non-invasive) exist for the determination of S-wave velocities, this article addresses the non-invasive generation and recording of S-waves to calculate velocities directly from traveltime measurements of reflected and refracted waves. This article is a contribution to an international effort to develop guidelines for practitioners (geophysicists and geological engineers) conducting seismic site assessments following requirements in building codes. Articles will be published in a forthcoming special issue of the Journal of Seismology in summer 2021.

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