Undergraduate Course: Measurement Techniques in Geophysics (EASC09024)
|School||School of Geosciences
||College||College of Science and Engineering
|Credit level (Normal year taken)||SCQF Level 9 (Year 3 Undergraduate)
||Availability||Available to all students
|Summary||This course provides an introduction to measurement techniques as applied in geophysics. Students follow a prescribed programme of numerical and physical experiments, carried out independently at times to suit the student. Three physical experiments aim to determine the physical properties of Earth materials in the laboratory (Density, Thermal diffusivity, Seismic velocities) and two numerical experiments are completed to model Earth structure at the field scale (Gravimetry and statistical data analysis and Satellite remote sensing and height measurement).
The course has five modules involving lectures, laboratory work and individual study. Each module will begin with a lecture. You will then have one week to attempt the practical in your own time. There will then be a three hour practical surgery one week later at which demonstrators will be available to help with any problems. A written report must be submitted two weeks after the practical surgery.
Lecture 1 Introduction to Measurement Techniques
Introduction to the scientific method. Scientific report writing, writing a good abstract. Handling errors in scientific measurements. Accuracy and precision in measurements. Reduction of random errors in measurements.
Lecture 2 Gravitational free fall application of precise length and time measurement
Newtonian equivalence principle. Equation of motion for constant gravity. Worked example to illustrate perturbation methods in order to find the equation of motion when gravity decreases with height. Effect of drag. Experimental design.
Optical wavelength as a practical length standard. The Döppler shift and line broadening. Lasers and the Fabry-Perot interferometer. Absorption spectroscopy. The iodine-vapour absorption cell and the J-M Chartier dithered laser. The modified Michelson interferometer and fringe counting. The rubidium vapour atomic clock
Lecture 3 Satellite orbits - the unperturbed two-body problem
The perturbed two-body problem - effects of the Earth's equatorial bulge on the Earth and the satellite. Kepler elements and real satellite motion.
Lecture 4 Analysis of the thermal diffusivity problem, solutions and experimental design.
Theory of thermal conduction in cylindrical coordinates and introduce Bessel & Kelvin Functions.
Two-surface versus one-surface boundary conditions end effects and reason for choosing cylindrical geometry.
Lecture 5 Seismic velocities
P and S waves. Determinating seismic velocities from seismic data, well logs and laboratory measurements. Issues associated with the upscaling of seismic velocity measurements made at very different scales.
Note: The content and number of practical modules may change: the following are indicative. Some will be group work.
Module 1 Gravimetry and statistical data analysis -Computer exercise
Precise gravity measurement in the field measuring the vertical gradient of gravity, the mean Earth radius and the mass of the Earth.
Statistical analysis of absolute gravity meter data. Random noise and its reduction by repeat measurements; random walk formula. Modelling systematic errors iodine stabilised laser and laser frequency dither; vertical gradient of gravity, speed of light.
Module 2 Satellite remote sensing - Computer exercise
Construction of satellite footprint tracks for different inclinations, altitudes and eccentricities. How to achieve a trade-off between the period of track repetition and spatial resolution. Examples for key satellite programs (TOPEX-Poseidon, GRACE, MAGSAT).
Module 3 Thermal diffusivity of a rock core ¿ Laboratory and computer exercise
Laboratory work: students (working in pairs in their own time) acquire temperature time-series on the axis of a cylindrical rock core subject to a square-wave temperature cycle on its outer surface. Uses ice bath and a domestic vegetable steamer. Data analysis, spectral analysis (computed with supplied program)
Module 4 Rock density - Laboratory and computer exercise
Laboratory use of micro-balance to determine density of a more-or-less non-porous rock (Silurian Tweeddale mudstone); effect of air wand water densities.
Computer exercise: use UK gravity database to estimate average terrain density in 10 km squares by a modified Nettleton's method. Investigate terrain density in Southern Uplands. Instabilities when model is inappropriate. (Programs supplied.) Laboratory use of microbalance to estimate saturated density, dry density and porosity for New Red Sandstone samples. Laboratory use of microbalance to determine density of granite chippings, peridotite fragments from a kimberlite xenolith, and an iron nickel alloy.
Module 5 Seismic velocities ¿ Laboratory exercise
1) Measure compressional wave velocity of hand sample of standard rock types.
2) Compare densities estimated using Birchs Law with measured densities.
Information for Visiting Students
|High Demand Course?
Course Delivery Information
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On completion of this course, the student will be able to:
- Develop skills for analysing observational data including examples of statistical and numerical methods, graphical interpretation and computing modelling.
- Gain experience and understanding of the design and process of physical measurement in a geophysical context.
- Be able to relate laboratory rock properties to bulk quantities met in geophysics.
- Be able to appreciate the principles of modern satellite-based observing platforms.
- Improve your ability to write proper scientific reports and extended abstracts, as well as deriving and collating information from the web and other literature.
|Blackwell, J &Martin, J., 2011, A Scientific Approach to Scientific Writing, Springer|
Gauch, H.J., 2012, Scientific Method in Brief,, Cambridge University Press.
Electronic versions of both the above books are available from the University library.
Berendsen, J.C., 2011, A student's guide to data and error analysis, Cambridge University Press.
|Graduate Attributes and Skills
|Additional Class Delivery Information
||There will be laboratory work in unscheduled hours.
|Course organiser||Dr David Wright
Tel: (0131 6)50 2539
|Course secretary||Ms Casey Hollway
Tel: (0131 6)50 8510