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TitleA compilation of microtremor horizontal-to-vertical spectral ratios (HVSRs) and borehole shear-wave velocities of unconsolidated sediments in south-central Ontario
LicencePlease note the adoption of the Open Government Licence - Canada supersedes any previous licences.
AuthorHunter, J A; Crow, H LORCID logo; Dietiker, BORCID logo; Pugin, A J -M; Brewer, K; Cartwright, T
SourceGeological Survey of Canada, Open File 8725, 2020, 12 pages, Open Access logo Open Access
PublisherNatural Resources Canada
Documentopen file
Mediaon-line; digital
File formatreadme
File formatpdf; rtf; xls (Microsoft® Excel®); jpg (Adobe® Reader®); saf; txt
NTS30M; 31D; 40P; 41A
AreaToronto; Niagara Peninsula; Wasaga Beach; Waterloo; Lake Ontario; Georgian Bay
Lat/Long WENS -82.0000 -78.0000 45.0000 43.0000
Subjectssurficial geology/geomorphology; geophysics; Science and Technology; Nature and Environment; seismology; earthquakes; boreholes; seismic methods; seismic waves; s waves; seismic velocities; amplitude spectra; sediments; glacial deposits; moraines; geophysical logging; seismographs; Oak Ridges Moraine; Waterloo Moraine; Phanerozoic; Cenozoic; Quaternary
Illustrationslocation maps; tables; plots
ProgramPublic Safety Geoscience
ProgramGroundwater Geoscience
Released2020 06 09
Horizontal-to-vertical spectral ratios (HVSRs) of microtremor-generated ambient noise were obtained at 41 borehole sites in South Central Ontario in the 2015-2017 field seasons, where in-hole measurements of shear wave velocity-depth structure had previously been made. It has been shown that HVSR spectral resonance maxima are directly correlated either to the presence of large seismic impedance contrasts within the unconsolidated sediments above the bedrock contact, or to the sediment-bedrock boundary. Ongoing research is currently examining the peak amplitudes and shapes of the HVSR resonance maxima in order to correlate with known subsurface structure of unconsolidated sediments in Canada. This present work is a contribution towards such correlations with respect to variable shear wave velocity structure, as shown through comparison of downhole velocity logs with co-located microtremor HVSRs.
Summary(Plain Language Summary, not published)
During the field seasons of 2015-2017 ground movements from micro-earthquakes were recorded at 41 sites in South-Central Ontario. These sites are very close to boreholes where in-hole shear-wave velocity measurement were previously made and where the types of sediments at depth from the surface are known. Ground movements are analysed in terms of movement strength per direction (up-down, east-west, north-south) and frequency, which allows an estimation of the depth of the movements. Finally, movement strength, shear-wave velocities and sediments over the full depth of the boreholes are compared.

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