PHYS/GEOL 406 Homework
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   Homework #9: Due Friday, April 3, by 5:00pm.


  • section 5.8 (all of it)
  • section 5.9.1. The numbers in the talbe on page 325 are good to keep in mind for various resistivity surveys. These will give you an idea of what to expect.
  • section 5.4.4 and Figs. (5.13) and (5.14) are really useful for seeing how the lines of current spread out when they cross various boundaries.
  • Eq. (5.19) has the "Snell's Law" version for the current flow lines when crossing from one material to another. Fig. (5.12) is a good visual.
  • Eq. (5.25) had the reflection coefficient, and it's drawn out in Fig. (5.16.a).
  • Recall that MagMap2000 is available from Geometrics, Inc. and RES2DINV is available from Geotomo Software. You need to be able to use these effectively.
  • This is a really good website. Seriously.
  1. problem 5.2. Here you need to give the specific angle in the lower material. Let the initial angles in these problems be (a) 65° and (b) 28°.
  2. You are in an area where sandy soil (see page 325) with ρ=150Ωm overlies damp clay with ρ=30Ωm, which overlies bedrock with ρ=2,000Ωm. Find the reflection coefficient for each interface.
  3. Discuss briefly (i.e. 1-2 sentences) which location would be better--and which would be worse--for performing a galvanic resistivity survey, either (a) southern Lousiana or (b) on a beach on an island such as Bermuda.
  4. Prepare a short write-up about the campus resistivity survey performed on March 26, 2015. Your final product will be a easily-interpreted cross section of the ground, along with a short, clear narrative of what the cross section reveals. I do not want a lot of discussion about what may or may not be known through other methods--this is to be focused on what the resistivity reveals. As we did in the lab, clean up the final image as we discussed. Be sure that you briefly discuss the type of electrode configuration used. The goal is to make this clear and professional, something that you would present to an employer.

That's all for homework #9.