List of Figures

  1. Example use of bplt to generate Post Script plot of down-hole data. Traces are plotted by geophone elevation. Data from a Boise River gravel borehole, B5.
  2. Example use of bplt to focus in on a single signal, trace 41.
  3. Example use of the psplot script. Data are rescaled by the L2 norm (option 3) of each trace before plotting by bplt
  4. Using bplt to focus on trace 41 from 50 to 60 msec in time.
  5. Using Seismic Unix (SU) to plot BSEGY data, script psPlot-su used.
  6. Plot of surface wave data using qplt. The qgraph.gp output file was edited to make a Postscript figure, and that is shown here.
  7. First trace of figure 6 surface wave data using tplt.
  8. Plots produced by traplt.m. (A). Time domain (B). Frequency Domain
  9. Plots produced by profplot.m.
  10. Source generates both horizontal and vertical motion
  11. Plan view of a typical survey. Coordinate system for geophone components and impact forces.
  12. PCA result (file h141plt.ps) for near surface geophone station.
  13. Deepest level (A) is 180 degrees off from desired as shown in (B)
  14. Plot of channel 2 and channel 3 geophone azimuth headers. The apparent discontinuity at about 12.5 m depth is exaggerated by channel 3 passing through North, 0 deg. = 360 deg.
  15. Plots produced by hodoplot.m confirms that data were rotated as desired
  16. Difference of Source Polarizations, T-Component (bequ applied to twav.seg)
  17. Sum of Source Polarizations, V-Component (bequ applied to pwav.seg)
  18. Alignment T-component data by first break picks for QC
  19. T-component Data Travel Time Inversions (a) Vertical Time (b) Observed Time
  20. Velocity analysis QC plot from file bvasqc.ps
  21. Summary plot showing velocity and semblance.
  22. Amplitude decay analysis QC plot from file bampqc.ps
  23. Summary plot showing decay as a function of frequency
  24. Merged figure showing both velocity and decay
  25. Sample of cafwd3 calculations. (A) run without data (B) run with data for comparison
  26. Sample of cafwd3 calculations. Quality factor varies with frequency.
  27. Base map for refraction survey along road shoulder.
  28. Plots generated with refplot.m.
  29. Choosing an estimate of the cross-over distance at 30 meters.
  30. Direct wave raypaths used by program direct.m
  31. Solution for overburden velocity is 923 m/s based on k004.seg, k008.seg, and k009.seg.
  32. Simplified delay time setup. Shots A and B shoot into geophones 1 and 2.
  33. Delay time solution for line along road shoulder. The structure plot has been squished vertically to remove most of the vertical exaggeration in a simple figure.
  34. Base map for refraction survey (line 3 goes up hill from the roadway)
  35. Scaled k011.seg refraction data
  36. Trace 20 as seen in segpic.m run
  37. Line 3 solution, merged xfig plots. A). Arrival times and fit, B). Structural Solution (accepted), C). Overburden velocity solution (rejected)
  38. Reciprocal shooting for refraction surveys across rivers. Bridge foundation investigations benefit from placing the geophones on land, and the source suspended from the bridge in the river.
  39. Array forming and filtering to enhance higher frequencies were needed to pick refractions. (A) shows an array formed record with strong Rayleigh and SV wave content. (B) is a blowup of the shallow data enhanced for P-waves by filtering.
  40. Solution from delaytmR.m analysis of 6 common geophone records and 3 constraints. Note, even after squishing the plot, there is about 12:1 vertical exaggeration on the structure.
  41. Color plot of semblance for example soil profile of Figure 42. The fundamental mode appears as red. A weaker higher mode is also visible as a lighter shade of blue.
  42. Example Rayleigh wave model with 0.1 meter step interpolation between control. The interpolation is linear in elastic modulus or density. See section 7.3.2 for additional details.
  43. Phase velocity computed by program disper for the model of Figure 42.
  44. Source wavelet for synthetic Rayleigh wave seismogram, model of Figure 42.
  45. Synthetic vertical component Rayleigh wave seismogram, model of Figure 42. See section 7.3.6 for further details.
  46. Manual modeling with FwdR1.m, final trial (A) dispersion and (B) soil profile. Vs30 is in the title bar of (B) assuming parameters remain constant down to 30 meters.
  47. Automated modeling with invR1.m. Initial model and intermediate models are shown in cyan. The 3rd, terminating iteration, is shown in red. The fit can be compared to that achieved in Figure 46. The model is shown for the 3rd iteration and is tabulated in the caption of (B). Note that both velocity and depth of control points were free to vary.
  48. Automated modeling with invR1.m. (A) Dispersion as a function of wavelength. (B) Singular values sorted by size. Only the 3 largest singular values were used (P=3).
  49. SASW recording places two geophones about a center line. The FFT is used to perform a cross correlation between the two signals in the frequency domain. The phase velocity dispersion curve is computed from the phase of the cross correlation and knowledge of the geophone spacing. Unwrapping of phase is required to compute dispersion beyond the spatial Nyquist frequency.
  50. (C). Geologan down-hole data. Octave program yulewalker.m is used to select trace 30. (A) Picking a length of the autocorrelation (nlag=116), (B) Downhole data, (C) Selected signal trace 30, (D) Yule Walker all pole spectral estimate.
  51. (A) Picked portion of autocorrelation. Sets spectrum order at 156. (B) Input file from bstk of bxcr. (C) Plot of the selected trace 30. (D) All pole amplitude spectrum.
  52. Solution to Lamb's Problem (after Mooney, 1974 (15)). Step function source.
  53. Synthetic seismograms generated by lamb (see text for model)
  54. Near and Far Field computations (source in x1, motion in x1 directions). The data have been trace qualized by the L2 norm of each offset signal to prevent fading of the motion due to amplitude decay.
  55. Simple layer over a half space model used in the gendis man page.
  56. Phase velocity curves computed for model in Figure 55.
  57. Motion-stress vectors for simple layer over a half space model of Figure 55. A) Displacement vectors, B) Stress vectors. Horizontal motion is R1, vertical motion is R2. Horizontal stress is R3, vertical stress is R4.
  58. Plot of vertical component motion, trace equalized to remove amplitude decay with offset. This permits viewing the waveform changes with offset. Compare this to the horizontal motion in Figure 60.
  59. Group velocities are available by plotting matu.m from within Octave.
  60. Plot of horizontal component motion, trace equalized to remove amplitude decay with offset. This permits viewing the waveform changes with offset. Compare this to the vertical motion in Figure 58.
  61. Wavelet plot from Octave program m0.m. Note that the bandwidth is less than conventional definitions would imply. When you set (fmin,fmax) in waves.d, you are basically setting nearly the complete limit of frequencies. The program reduces the bandwidth to approximately $4fmin$ and $fmax/2$ . This figure has been enlarged to show detail with the axis command.
  62. Plot of file bdifwavV.seg, differentiated wavV.seg simulates what a velocity geophone might see. Compare to Figure 58.
  63. Plot of file bdifwavV.seg, differentiated wavV.seg simulates what a velocity geophone might see. Only near offset signals are shown for easier comparison.
  64. (A). Correct waves computation of dispersion. (B). Illustrates too large a depth difference between top and bottom of the discontinuity. The solution is to make the discontinuity more abrupt in disper.d or decreasing stepz in waves.d to remove the glitches.
  65. (A). Kelvin-Voigt (KV) representation for both vibrator and wave assemblage. (B) Kelvin-Voigt-Maxwell-Biot (KVMB) representation.
  66. Octave program, kvKVMBscan.m, can be run to illustrate the effects which largely depend on porosity. Shown are cases for different mass ratios of solid frame and pore fluid.
  67. Octave program, kdKVMBscan.m, can be run to illustrate the effects which largely depend on porosity and frequency of shaking. Shown are the case for 15 Hz shaking. The user can choose a horizontal axis of either (A) hydraulic conductivity (m/s), or (B) “pore diameter (mm)”
  68. Octave program, fqKVMBscan.m, can be run to illustrate the relationships possible between hydraulic conductivity and KV damping ratio, the metric for viscous friction.
  69. Octave program, KD4kvmb.m prompts the user for porosity (n), stiffness ($C_1 $), damping ($C_2 $), frequency of shaking and related uncertainties. Then when run, a display of the solution is given in a message box. Also show is the graphical image of the process. The $C_1 $ and $C_2 $ values produce a KV damping ratio that is represented by the horizontal line that intersects the KVMB to KV curve. The two intersections are the solution.