Misleading interpretation of shallow seismic methods: Three case studies from MASW, P-wave refelection and shwave reflection surveys

Ahmed M. Ismail, Yevgeniy A. Kontar, Edward C. Smith, Andrew C. Phillips, Andrew J. Stumpf

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Despite the reliable performance of high resolution seismic methods for imaging the shallow subsurface, in some cases interpreting seismic results can be misleading. We present three case studies where results from, P-wave reflection, SH-wave reflection, and MASW surveys were incorrectly interpreted because of inadequate constrains on either the surface or subsurface conditions of surveyed sites. A feature from a P-wave reflection survey was first interpreted as a shallow fault zone, but it was later] determined to result from a high level of background noise as the acquisition passed through a road intersection. A feature from an SH-wave reflection survey was interpreted to be a reverse dip-slip fault, but targeted drilling showed it was deep local erosion into the bedrock surface. Finally, in an MASW survey, a steeply dipping feature was first interpreted as a bedrock valley. However, later exploratory drilling showed the feature to be a shallow layer of very soft lake sediment that severely damped most of the applied surface wave frequency band. Although initial interpretations were incorrect, they stimulated discussions among geophysicists and geologists and underscored the need for meaningful cooperation and discourse between the scientists before, during, and after geophysical data acquisition.
Original languageEnglish (US)
Title of host publication22nd Symposium on the Application of Geophysics to Engineering and Environmental Problems 2009, SAGEEP 2009
PublisherEnvironmental & Engineering Geophysical Society
Pages20-29
Number of pages10
ISBN (Print)9781615670512
DOIs
StatePublished - 2009
Event22nd Symposium on the Application of Geophysics to Engineering and Environmental Problems 2009, SAGEEP 2009 - Fort Worth, TX, United States
Duration: Mar 29 2009Apr 2 2009

Publication series

NameProceedings of the Symposium on the Application of Geophyics to Engineering and Environmental Problems, SAGEEP
Volume1
ISSN (Print)1554-8015

Other

Other22nd Symposium on the Application of Geophysics to Engineering and Environmental Problems 2009, SAGEEP 2009
Country/TerritoryUnited States
CityFort Worth, TX
Period3/29/094/2/09

Keywords

  • ISGS

ASJC Scopus subject areas

  • Geophysics
  • Geotechnical Engineering and Engineering Geology
  • Environmental Engineering

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