Table of Contents
Seismic Surface-Wave Tomography of Waste Sites Project ID 55218 Grant # DE- FG07-96ER14706
Leland Timothy Long Georgia Institute of Technology School of Earth and Atmospheric Sciences Atlanta, GA 30332-0340 (404) 894-2860 tim.long@eas.gatech.edu
PPT Slide
Waste dumped on the surface or buried in shallow trenches can contaminate the surrounding rock and soil. The shear-wave velocity is sensitive to changes in soil properties and can be used to map structures that affect containment of the waste. A three dimensional mapping of shear-wave velocity can assist in evaluations of contaminated sites, in addition to locating buried trenches. The sensitivity of shear-wave velocity to fluid content makes it useful for identification of zones of saturated waste fluids and for tracking fluid movement with time. This research demonstrates that it is possible to generate images of shallow shear-wave structure from measurements of surface-wave group-velocity tomography. Images at test sites confirm the presence of anomalous structures.
Why Use Surface Waves
Comparison With Other Methods
Spectral Analysis of Surface Waves (gives depth structure between sensors)
Refraction line. This synthetic example shows the small signal level of P-waves relative to surface waves.
Why Group Velocity
What is Group Velocity
PPT Slide
Why Use Tomography
Ray Geometry and Hit Density
Typical Shot Record
Calculating Group Velocity
Examples of Filtered Traces
Correction for group delays
PPT Slide
Optional Inter-Station Constraint
Tomographic Inversion
PPT Slide
An average dispersion curve and an average structure are found.
PPT Slide
PPT Slide
PPT Slide
PPT Slide
PPT Slide
PPT Slide
PPT Slide
PPT Slide
PPT Slide
Velocity Structure
Conclusions
|