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Full Year

Geophysical Measurement and Modelling (EASC10110)

Subject

Earth Science

College

SCE

Credits

20

Normal Year Taken

3

Delivery Session Year

2023/2024

Pre-requisites

Approval of the Course Organiser.

Course Summary

This course is mainly about geophysical measurement and modelling, with selected practical examples. It includes the theory of geophysical fields and waves and both passive and active geophysical measurements. It also includes a lecture and practical on meteorological measurements. The course includes Fourier analysis and filter theory, which form the rationale for the sampling and manipulation of the data. The course introduces examples of the measurement of geophysical parameters both in the field and in the laboratory, with special attention to the handling of uncertainties in measured quantities. Practical exercises involve both acquisition and interpretation of the data.The five practicals are distributed over the two semesters three in Semester 1 and two in Semester 2, with the relevant theory introduced before each practical, wherever possible.

Course Description

Semester 1 Week 1. No lectures or practicalsWeek 2. Introductory lecture. Telegraph equation. Handling errors in scientific measurements. Accuracy and precision in measurements. Scientific report writing.Potential fields: Newton's law of gravitation; gravity; gravitational potential; Laplace's equation; Poisson's equation; force due to electric charge and magnetic poles.Week 3. Satellite orbits, Kepler elements and satellite motion.Practical 1: Gravimetry and statistical data analysis - Computer exerciseWeek 4. Acoustic wave equation: total time derivative and partial time derivative; acceleration of a particle; linearization; equation of continuity; pressure waves in a fluid; constitutive equation; 1-D, 2-D and 3-D acoustic wave equations; solution to the 1-D wave equation.Week 5. Feedback on Practical Report 1. Practical 2: Determining density of Silurian mudstones. - Laboratory and computer exercise.Week 6. Seismic waves: components of strain and stress; equations of motion in an elastic medium; Hooke's law of elasticity; elastic wave equations, P-waves and S-waves; particle motion of a plane wave; solutions to the wave equation; normal modes: oscillations of a string.Week 7 Practical 3: Thermal diffusivity of a rock core - Laboratory and computer exercise. Week 8. Fourier Analysis and Filter Theory, Part 1: Fourier transform; the delta-function; resolution and bandwidth; similarity theorem; impulse function; impulse response; linear filters and convolution; convolution theorem; derivative theorem; wavefield transformation.Week 9 Fourier Analysis and Filter Theory, Part 2: Sampling theorem and aliasing; filtering; correlation and autocorrelation; deconvolution; effects of noise; upward and downward continuation.Week 10 Electromagnetic (EM) Waves: Maxwells equations; EM constitutive relations; EM wave equations; plane wave solutions of the EM wave equations, skin depth, wavelength; EM propagation in air and free space; EM propagation in conducting media; diffusion equation.Week 11 Revision.Semester 2Week 1 Passive Geophysical Measurements, Part 1: gravity anomalies; gravity meters, measurements and corrections; gravity gradiometry and gravity measurement on a moving vessel or aeroplane; non-uniqeness of gravity interpretation; magnetics; heat flow.Week 2 Meteorological measurements: atmospheric turbulence.Practical 4: Meteorological measurements - Computing exercise. Week 3 Passive Geophysical Measurements, Part 2: The magnetotelluric method; classical seismology; Adams-Williamson equation.Week 4 Active Geophysical Measurements, Part 1: seismic exploration and seismic data acquisition; reflection coefficients for acoustic waves; seismic exploration and normal moveout correction and stacking;Practical 5: Seismic wave speed - Laboratory exercise.Week 5 Active Geophysical Measurements, Part 2: Controlled source electromagnetics (CSEM) and the role of fluids; conventional CSEM; transient CSEM and MTEM; Week 6 Greens theorem and some applications.Week 7 Seismic sources and receivers; dynamite, air guns, Vibroseis and determination of source time functions; geophones, hydrophones and their response functions.Week 8 Receiver functions: surface vector motion, P-S conversion, separation of P-wave from converted wave, P-wave and S-wave velocities in the crust and upper mantle. Week 9 Revision.

Assessment Information

Written Exam 50%, Coursework 50%, Practical Exam 0%

Additional Assessment Information

Assessment detailsExam (50%)Coursework (50%)The coursework consists of five practical exercises. The students are expected to do all five and write a report on each in no more than four pages. Written feedback will be provided on the first report. Each of the subsequent four-page reports will count for 12.5%. The reports will count for a total of 50%. The three-hour exam will be on the whole course, including the practical exercises, and will count for 50%.For information on deadlines please refer to the Learn page.Assessment deadlinesPractical Report 1 (formative) - Semester 1, 12:00 Wednesday (Week 4). Feedback on Practical Report 1 - Week 5 Practical Report 2 Semester 1, 12:00 Wednesday (Week 6).Practical Report 3 Semester 1, 12:00 Wednesday (Week 10).Practical Report 4 Semester 2, 12:00 Wednesday (Week 3).Practical Report 5 Semester 2, 12:00 Wednesday (Week 5).

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