Questions: Physical Properties and 7 Step Process 1. Why does a water-saturated sandstone typically have a higher P-wave velocity than a dry sandstone? A saturated sandstone: a. is more dense b. has a larger bulk modulus c. has a larger shear modulus d. has a higher tensile strength 2. The relative permittivity of a given rock is considered large when: a. it contains a lot of pore water b. an applied electric field results in a larger electric dipole moment c. it has a value of 30 d. b and c are correct e. a,b and c are correct 3. You measure a resistance of 16 kΩ between two parallel faces of a 2cm x 2cm x 2cm cube. Determine the resistivity. a. 320 Ωm b. 800000 Ωm c. 32000 Ωm d. 8000 Ωm 4. You are flying a gravity survey over a sedimentary basin. The flight path crosses a known dyke. What would be the expected gravity response and why? a. Gravity high over the dyke; the dyke is more dense than the background b. Gravity low over the dyke; the dyke is less dense than the background c. Gravity high over the dyke; the dyke is less dense than the background d. Gravity low over the dyke; the dyke is more dense than the background 5. You are building a road through known active Karst terrain in Ireland. Which set of physical property contrasts would be most diagnostic for locating regions where sink- holes could form? a. Karstified: low density, Limestone: high density b. Karstified: low resistivity, Limestone: high resistivity c. Karstified: high susceptibility, Limestone: low susceptibility d. Karstified: high seismic velocity, Limestone: low seismic velocity 6. You examine two rocks and determine they have the same density. However, you realize that both of them have distinctly different S-wave velocities. What is the BEST explanation for this? a. Density is the most important factor in determining S-wave velocity and we can’t explain this b. Both rocks have a different shear moduli c. Both rocks have a different bulk modulus d. A combination of (b) and (c) 7. Imagine a rock that contains BOTH ionic pore water AND ore-bearing minerals (ie. Magnetite or Sulphides). Where is the current flowing within the rock? a. The current will move almost exclusively through the rock because it contains extremely conductive minerals. b. The current will move almost exclusively through the ionic pore water because it is an unbroken, conductive pathway for the current. c. Depending on the rock, current will move through either the ionic pore water OR the minerals. Whichever path is the most conductive out of the two. d. Depending on the rock, current will move through both the ionic pore water AND the rock to varying degrees because they are both conductive pathways. 8. When considering minerals that contain iron, which out of the following statements is true? a. Minerals that contain iron aren’t necessarily susceptible or conductive b. Minerals that contain iron are almost always susceptible and conductive c. Minerals that contain iron are almost always susceptible, but aren’t necessarily conductive d. Minerals that contain iron aren’t necessarily susceptible, but are almost always conductive. 9. With regards to magnetic susceptibility, which of the following is INCORRECT? a. Magnetic susceptibility is a unitless quantity b. The magnetic susceptibility of a rock is dependent on the concentration of susceptible minerals (magnetite) within the rock. c. The magnetic susceptibility of a rock is also dependent on its size. d. Magnetic susceptibility describes the linear relationship between magnetism and the inducing magnetic field. e. Both a) and c) are incorrect. 10. Why is the following sentence WRONG? “Rocks are significantly denser when they are comprised of minerals containing metallic elements.” a. Almost all known minerals have chemical compositions containing metallic elements of some kind or another. This doesn’t mean they are dense. b. The sentence is only correct if you replace “metallic elements” with the word “iron”. c. This is a trick question. I stand by this statement. d. This statement is incorrect because they didn’t mention pore space. 11. You are about to perform a gravity survey to locate rocks that contain magnetite (because magnetite is dense). Why might you be UNSUCCESSFUL? a. If the concentration of magnetite within the rock is small, the rock may not be overly dense. b. No information regarding the background media was provided. For all we know, it has similar density because of some other mineralogy. c. If the subsurface is made up of a set of horizontal layers (our magnetite bearing layer being one of them), we would see not change in the gravity measurement by moving laterally across the surface. d. Both a) and b) explain why this survey might be unsuccessful e. Reasons a), b) and c) explain why this survey might be unsuccessful. 12. When planning to survey a region using geophysics, what of the following is the MOST important to consider? a. That you make sure your line spacing is sufficiently small so you can plot any observable anomalies with sufficient detail. b. That you choose a surveying method capable of exploiting the contrast in physical properties between what you are looking for, and the background rock. c. That you always remember to take multiple measurements at each position so you can average the readings and get good quality data. d. That you always survey using more than one method. That way, you can make sure you don’t miss anything. 13. Gravity surveys can be used to find dense rock in a less dense background and DC resistivity surveys can be used to find conductive rock in a more resistive background. Can you use the exact same methods to find less dense rock in a high density background and resistive rocks in a conductive background? a. No to both. The dense background rock would cloud gravity readings and the DC resistivity survey would fail because no current would flow through the more resistive rock and pick up information. b. Yes to both. In all cases there is a contrast in physical properties between the background rock and the rock of interest. c. The dense background rock would cloud gravity readings but the DC resistivity survey would still work. d. The DC resistivity survey would fail because no current would flow through the more resistive rock and pick up information. However, the gravity survey would still work 14. Which connections between geophysical prospecting methods and material properties are correct? a. EM - permittivity; GPR - permittivity; Magnetics - susceptibility; Seismic - density b. EM - chargeability; GPR - conductivity; Magnetics - resistivity; Seismic - velocity c. EM - conductivity; GPR - permittivity; Magnetics - susceptibility; Seismic - velocity d. EM - conductivity; GPR - conductivity; Magnetics - susceptibility; Seismic – density 15. What is the correct seven-step process? a. Setup, surveys, data, processing, properties, interpretation, synthesis b. Setup, properties, surveys, data, processing, interpretation, synthesis c. Properties, setup, surveys, data, processing, interpretation, synthesis d. Setup, properties, surveys, data, processing, synthesis, interpretation 16. Geophysical surveys can provide information about the distribution of a physical property. What is the principle difficulty encountered when trying to use this information to identify a rock type? a. There aren’t any real difficulties b. Different rock types can have different values of a physical property c. Different rock types can have the same value of a physical property d. A single sample of rock has multiple values of a physical property 17. Which statement in the list below is TRUE a. A buried object is detectable so long as it has a non-zero value of a physical property b. A buried object is detectable so long as it has a significant physical property contrast compared to the surrounding rocks. c. A buried object is detectable if its dimensions are larger than its depth of burial. d. A buried object is detectable if it has two physical properties that are not the same. 18. Which of the following would NOT usually be part of our 7-step framework? a. Choose the line spacing and station spacing for field data collection b. Carry out geophysical surveys in the field c. Answering a geologic or engineering question directly by looking at the survey data d. Forward model some synthetic models to understand expected responses 19. If you want to estimate how easy it will be to dig through some fractured rock, what physical property is likely to be the most useful? a. Electrical conductivity b. Seismic velocity c. Dielectric permittivity d. Magnetic susceptibility 20. In the seismic TBL, the geotechnical goal was to find the depth of till that lay beneath a shallow water table. Which of the following was likely to be most diagnostic? a. GPR survey b. P-wave refraction survey c. S-wave refraction survey d. EM-31 survey 21. If you wanted to locate a relatively near-surface sand and gravel quarry in a large area, which of the following strategies would be most appropriate? a. A dense seismic refraction survey b. An EM31 survey and followed up with a DC resistivity survey c. A GPR survey d. A magnetic survey 22. In real applications, a physical property is complicated because of its variability. Consider electrical conductivity. From the list below choose the scenario in which the electrical conductivity is the most uncertain. a. Buried steel pipe carrying sewage along Main Street b. Forested overburden on top of bed rock in Stanley Park c. Sea water in Burrard Inlet d. b and c 23. Which physical property would NOT likely have a large contrast with the background rock if a buried tunnel was the target in a homogenous limestone layer? a.