JGA305, fall 2019 – assignment: gpr
1. Two-way-time and reflection coefficient
You are running a GPR survey on a small lake. The freshwater is 3 m deep, underlain by 50 cm saturated sand, which sits on granite. Calculate the two-way times for reflections off the two interfaces as well as the reflection coefficients.
2. Comments on a paper (4 points)
Retrieve the following article from the U of T library system: “Three-dimensional ground-penetrating radar imaging of sedimentary structures, fractures, and archaeological features at submeter resolution” by M. Grasmueck, R. Weger, and H. Horstmeyer, Geology, vol 32, no 11, pg 933-936, 2004. and check out the corresponding movies at http://www.cslmiami.info/gpr/research
Answer the following question: How do the researchers create such fine images of the subsurface? (you will find that in the intro and method sections)
Sketch an annotated cross section of the Miami example (see section ”Oolitic carbonate anatomy”).
3. data interpretation (5 pts)
The directory on the course website contains GPR datafiles, and the SIGkit . Choose one of the data, determine a reasonable dielectric constant by fitting a hyperbola, and determine the depth of certain features (ex: depth of kettle lake, depth to buried pig, thickness of top layer at Whitefish).
Show a graph of the data, include at least 2 fitted hyperbolae, and annotate the graph with your interpretation of this data.
This assignment is due before next class, to be submitted electronically on the course website. If you do it by hand please scan your paper to submit electron- ically.
