GEOPH424 Midterm: GEOPHYS 424 UofA midterm Exams 424Midterm 2009
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Note the number of points allocated for each part. Notes and textbooks may not be used during the exam. Please hand in this exam, with your name and student number listed above. Question 1 resistivity of rocks ( total = 9 points) The pore space of a sandstone is 50% saturated with salt water. The salt water has a salinity of 10g per litre. The rock has isolated pores and a bulk resistivity of 50 m. The rock grains have a resistivity of 2000 m (a) what is the porosity of the sandstone ? (b) state two assumptions that you have made in answering (a) (4 points) (5 points) Question 2 : maxwell"s equations (total = 16 points) Low frequency electromagnetic (em) fields propagate in the earth and the displacement current can be ignored. The x-axis and y-axis are horizontal and mutually orthogonal. Question 3 : magnetotellurics (total = 12 points)
