Near-Surface Seismology

by Gregory S. Baker

Duration: Two days

Intended Audience: Geologists and geophysicists, both in industry and academia. Materials covered will be valuable to both explorationists and exploitationists who have interest in the upper 200m of the subsurface.

Summary:
More than ever before, people in academia and industry are using near-surface seismology as a noninvasive tool for determining the physical properties and geometry of the upper 200 meters of the subsurface. Traditionally, workers using seismic methods for academic or industrial purposes have been familiar with the use of the techniques for hydrocarbon or crustal exploration. Advances in seismic methods have come largely from "deep" exploration seismology because the drive underlying that industry is profit maximization. Seismic techniques involved with imaging from hundreds to thousands of meters below the surface of the earth, therefore, have had substantial monetary support to obtain the best data possible.

Major use of shallow-seismic techniques today, however, is in the environmental industry (for site characterization, contaminant detection, etc.) driven by minimizing cost. Therefore, if the availability of better data reveals a need for more expensive and extensive site cleanup, improving seismic data quality may be counter productive (to the industry) and may not obtain a high priority for funding and quality control.  The goal of this course is therefore to provide a starting point for near-surface seismology workers who have not had industry- or academic-supported training or guidance but wish to maintain the integrity of seismology as a tool for near-surface exploration.

Course Outline:
This course is designed to provide background information to help professionals and academics use and understand near-surface seismology techniques. We will cover the following:

  • Basic near-surface seismic theory
  • Instrumentation: including sources, seismographs, and sensors
  • Seismic refraction: including the generalized reciprocal method (GRM), and refraction tomography
  • Seismic surface waves: including spectral analysis of surface waves (SASW) and multichannel analysis of surface waves (MASW)
  • Seismic reflection: including common-offset and common-midpoint (CMP)
  • Seismic data integration and interpretation, including pitfalls and case histories

Course lectures will involve both PowerPoint presentations as well as "in class" paper exercises focused on interpretation and pitfalls. Due to the numerous data processing, analysis, and interpretation software packages available and necessary for in class work (and their associated licensing!), we will not be doing any computer-based data processing or analysis. However, appropriate step-by-step analyses of the procedures (including examples) will be covered.

Instructor Biography:
Gregory Baker