university of queensland instrumentation proton free-precession magnetometer optically-pumped...

ERTH3020 Introduction to Geophysics Semester 1, 2011

University of QueenslandCourse Profile

ERTH3020Introduction to Geophysics

Semester 1, 2011

Course Outline This elementary course introduces the main techniques used in exploration (or applied) geophysics, including the seismic, electrical, magnetic and gravity methods. The discussion incorporates basic theory, instrumentation, data processing and interpretation techniques. Practical classes are used to illustrate geophysical applications to real and synthetic data. The course spans one semester and is worth 2 units.

CoordinatorSteve Hearn Steele Building (3) Room 325 Email [email protected] Consultation: Tues, Thurs PM by email appointment

Exploration Geophysics Laboratory, University of Queensland, Australia


IMPORTANT INFORMATION FOR STUDENTS – PLEASE ABSORB THIS

Assumed background:

Basic mathematics (approximately Level 1) including basic algebra, calculus and trigonometry. A revision tutorial will be provided early in the course, which will serve to indicate whether students have adequate background. Introductory geology and physics are recommended but not essential. Contact Steve Hearn for further details.

Class contact hours:

Weekly: 2 blocks (2 hours + 3 hours) Steele Building: 221/222Weekend Field Trip (date to be confirmed). Cost: approximately $150 (including food, campsite, transport).

Email Contact:

From time to time, I will use email to provide students with various course material, updates etc. Early in semester I will send a test email to all enrolled students. It is your responsibility to ensure that you are receiving mail, and to check your mail regularly.

Web page:

Various course download material will be placed on the web at the following address: www.geoph.uq.edu.au/erth3020. I can update this more conveniently than other download sites.

Calculators:

Standard scientific calculators are essential for tutorial and examination work. Students are asked to perform interactive calculations in class. Programmable calculators are not to be used to store information for use in examinations.



IMPORTANT INFORMATION FOR STUDENTS – PLEASE ABSORB THIS

Assessment:

In 2011 the breakup of marks for this course is:Mid-Semester Examination 40%, Final Examination 40%, Practical Work 20%.NOTE: In order to pass this course, a passing grade must be achieved in both the examination and practical components.

Each examination will be of duration 2 hours. Students must answer 3 out of 4 questions.Detailed requirements for each tutorial will be given at the start of each tutorial session.

Attendance Policy:

There is no formal penalty for failure to attend lectures or practicals. However, attendance is strongly encouraged. Practical material is difficult to comprehend without prior attendance at the relevant lectures. In addition, completion of pracs depends heavily on interactive input from staff. Practical work can be largely completed in the scheduled sessions.

Important Dates:

Mid-Semester Examination: April 14 (10AM)Practical Submission: June 7 (5PM)Final Examination: June 14 (10 AM)Field Trip: To be confirmed

Submission of Practical and Assignment Material:

Deadline for submission of all practical material and field-trip report: 5pm Tuesday 07 June 2011All practical and assignment material must be submitted in hard-copy form through the School of Earth Sciences office. Please ensure that you receive a receipt for your submission.

Late Submission Policy:

Late submissions will incur a deduction of 20% of the available marks for each day beyond the deadline. For example, a student submits a component worth 10 marks 2 days late. Based on content he is awarded 8/10. Because the submission is 2 days late he incurs a penalty of 0.2 * 2 * 10 = 4 marks. The final mark is then 4/10.



COURSE CONTENT

Lectures and Practical material will be drawn from the following. The Electronic Course Profile gives indicative scheduling.

Introduction

Geophysics – an integrated scienceGlobal geophysics and exploration geophysicsGeophysical Methods

Gravity 1. Introduction

Basis of the gravity methodDensities of common materialsMagnitude of gravitational variations

2. Basic Theory and TerminologyNewton’s Law of Universal GravitationGravitational field, gravitational acceleration, gravitational potentialUnits of gravitational accelerationGravitational Acceleration due to a finite massGravity anomaly / density contrastComputing gravity anomalies analytically and numerically

3. Gravity Instrumentation Basic concept of spring gravity meterProblem of sensitivity vs compactnessDesign enhancements for the spring gravity meter

4. Gravity Acquisition and ProcessingField techniques, base station techniques Correction of Gravity Readings (drift, latitude, free air, Bouguer)

5. Airborne Gravity MeasurementsThe gravity gradient The Falcon system



Magnetics

1. Introduction Overview of the basis, instrumentation and applications of the magnetic method.

2. Basic Theory and TerminologyMagnetic field strength, flux density, absolute permeabilityRelative permeability, susceptibility, magnetisationHysteresis

3. Magnetic Properties of RocksMagnetic phenomenaSusceptibilities of common rock typesRemanent magnetisation

4. The Geomagnetic FieldThe Earth as a 'bar magnet'Intensity, Inclination and declination

5. Magnetic InstrumentationProton free-precession magnetometerOptically-pumped magnetometer

6. Magnetic Field ProceduresOperator precautionsDrift Corrections

7. Interpretation and ModellingQualitative InterpretationQuantitative InterpretationNumerical modelling

Electrical Resistivity

1. IntroductionBasis of the methodFactors controlling conductivity of rocks

2. Basic TheoryReview of basic electronicsResistivity and conductivityOhm’s Law in the earthPotential due to a point electrode



3. Measurement of Resistivity using Electrode ArraysPotential difference in a general four electrode arrayThe concept of apparent resistivitySome common array typesConsiderations in array selection

4. InstrumentationCurrent circuitPotential measuring circuitMeasurements and calculations

5. Electrical Sounding Depth Investigation CharacteristicField methodology for different arraysEquivalence and suppressionInterpretation techniques

6. Electrical ProfilingField methodology for different arraysPseudosections

Other ‘Electrical’ Methods

1. Spontaneous PotentialIntroductionTypical SP anomalyOrigin of SP effectsPractical aspects

2. Induced PolarisationIntroduction – The IP EffectTime Domain measurementsFrequency Domain MeasurementsApplications of IP

3. Electromagnetics

Introduction – The EM conceptElectromagnetism and Electromagnetic InductionGeneralised concept of EM explorationExample – the Slingram systemAirborne EMTransient EM (TEM)Magnetotellurics (MT)Ground Penetrating RadarAdvantages and disadvantages of EM



Seismic Methods

1. Basic Concepts of the Exploration Seismic Method

P and S waves; surface waves (Love and Rayleigh); seismic velocity; acoustic impedance; Snell’s Law; wavefronts; ray paths; reflection and transmission coefficients; practical examples of different lithologies; elastic constants.

2. Seismic Refraction – Basic Theory

Physical basis of refraction; head waves; critical angle; ray paths and travel time equation for simple plane horizontal layer model; extension of travel time equations to multiple layers.

3. Seismic Refraction – Slope Intercept Method of Interpretation

Interpretation of simple horizontal-interface models. Ambiguities introduced by dippping interfaces. Depth and velocity interpretation procedures for 2 and 3 layered models.

4. Seismic Refraction – Reciprocal Method Interpretation

Reversed refraction shooting; calculation of the time-depth; physical significance of time-depth; time-depth to depth conversion; velocity analyses techniques; generalized reciprocal method.

5. Seismic Refraction – Logistics

Refraction instrumentation; sources; shooting patterns; data processing; applications of refraction.

6. Seismic Reflection – Theory

Geometry of reflection; travel-time equations; normal moveout (NMO); reflection coefficients revisited; CMP stacking.

7. Seismic Reflection – Logistics

CMP acquisition techniques; reflection sources; geophones; recording instruments; fundamentals of reflection data processing.

8. Seismic Reflection – Interpretation

Example reflection records; seismic sections; appearance of faulting and folding; applications in petroleum, coal, engineering and crustal studies.



References

There are no set texts. The following hardcopy references are available in the Physical Sciences and Engineering library.

Sheriff, R.E., Encyclopedic Dictionary of Geophysics, 3rd Edition, SEG.Telford, W., Geldart, L., Sheriff, R., Applied Geophysics, Cambridge University Press.Sheriff, R.E. and Geldart, L.P., Exploration Seismology. Cambridge University Press.

Main Course Reference Site:

www.geoph.uq.edu.au/erth3020

Useful Starting Web References – Gravity Method

pubs.usgs.gov/fs/fs-0239-95/fs-0239-95.pdfhttp://en.wikipedia.org/wiki/Newton's_law_of_universal_gravitationhttp://falcon.bhpbilliton.com/falcon/http://appliedgeophysics.lbl.gov/

Other useful URLs will be given as the course progresses.


http://falcon.bhpbilliton.com/falcon/


Teaching and Learning Methods

Lecture and practical materials are closely integrated so that concepts from lectures are reinforced in associated tutorials. Since this is an applied discipline, it benefits from an interactive style of learning. Hence it is essential that students attend classes in person. Conceptual understanding is emphasised rather than 'rote learning'. This enables students to tackle varied application-style problems in tutorials. If students do not follow concepts, they will find it difficult to cope with applied tutorials and examination problems. Lecturing staff encourage interactive questioning during lectures, as needed to clarify concepts. A range of handout material is provided, as well as references to digital sources. However it is considered essential that students also take additional notes. This is of value for capturing the emphasis and flavour delivered by the lecturers, as well as more detailed factual material.

For each tutorial exercise, students are generally provided with handout material covering the core procedures, as well as data samples. As a rule, however, the effective execution of the tutorial requires considerable interaction with staff. For this reason it is important that the tutorial work be carried out in the allocated time period. Generally it will be difficult to successfully negotiate the tutorial without some input from staff. Tutorials are planned such that all critical aspects can be easily completed within the allocated time period. At the end of each tutorial session, the student should retain his work. This may be useful for examination revision. All tutorial work is handed in for final assessment at the time of the examination.

Standard scientific calculators are essential for tutorial and examination work. Programmable calculators are not to be used to store information for use in examinations.

Students should be familiar with the rules which relate to assessment in their degrees as well as general university policy such as found in the General Award Rules. These are all set out on the myAdvisor page on the UQ website http://www.uq.edu.au/student/GeneralRules2003/2003GARs.htm.



Assessment Criteria

Answers to written examination questions, tutorial exercises will be assessed in terms of the extent to which they demonstrate the ability of the student to: • Define, explain and interrelate the key concepts involved in the course. • Use the basic theory to describe quantitatively the behaviour of important geophysical techniques treated. • Apply theory to particular geophysical problems and obtain correct analytical and numerical results in the appropriate units of measurement. • Use appropriate mathematical approaches to derive geophysical relationships. • Have an appreciation of the orders of magnitude of important quantities. • Analyse provided geophysical data and present qualitative and or quantitative results.

Field trip assessment, if required, will be based on: • Demonstration of a responsible and cooperative attitude in the field. • Logical analysis and presentation of field results.

Criteria for the award of grades Your grade for this course will be determined by the levels of achievement that you consistently display in the items of summative assessment. These may be formally defined as follows:

Grade of 7: the student demonstrates an excellent understanding of the theory of the topics listed in the course outline and is highly proficient in applying the techniques to solve both theoretical and practical problems. Grade of 6: the student demonstrates a comprehensive understanding of the theory of the topics listed in the course outline and is proficient in applying the techniques to solve both theoretical and practical problems. Grade of 5: the student demonstrates a good understanding of the theory of the topics listed in the course outline and can apply the techniques to solve problems. Grade of 4: the student demonstrates an understanding of the theory of the topics listed in the course outline and demonstrates a knowledge of the techniques used to solve problems. Grade of 3: the student demonstrates some understanding of the theory of the topics listed in the course outline and demonstrates a knowledge of the techniques used to solve problems. Grade of 2: the student demonstrates limited understanding of the theory of the topics listed in the course outline and demonstrates limited knowledge of the techniques used to solve problems. This includes attempts at expressing their deductions and explanations and attempts to answer a few questions accurately. Grade of 1: the student demonstrates very limited understanding of the theory of the topics listed in the course outline and of the basic concepts in the course material. This includes attempts at answering some questions but demonstrating very limited understanding of the key concepts.

As a guide, the following overall percentages are indicative of typical numerical boundaries for the lower limit of Grades 7 -3: 85%, 75%, 65%, 50%, 45%. Note that from 2006 a grade of 3 is considered a failing grade.



Course goals/rationale

On completing this course students will: • have a basic understanding of the core techniques used in exploration geophysics • understand important terminology used in exploration geophysics • have an introductory exposure to geophysical field equipment and practices • be able to work with real geophysical data at an introductory level

Graduate Attributes

The following graduate attributes will be developed in the course –

In-Depth Knowledge of the Field of Study • Introductory understanding of the major geophysical techniques • An understanding of how the different geophysical techniques interact • An understanding of how geophysics interacts with associated disciplines such as geology and engineering

Effective Communication • The co-operative nature of practical and field work promotes effective interaction and communication in both small team and larger group situations. • Data from practical and field work need to be collated, analysed, and communicated via a formal report.

Independence and Creativity • Exploration Geophysics is a reality-based arena, where established techniques are constantly being adapted to suit particular conditions. Field and practical experience encourages and develops students’ capacity for independent work and flexible innovation. Students are also, as always, required to undertake independent study and learning in order to develop a sound knowledge of geophysics, as a basis for such innovation.

Critical Judgement • The ability to detect spurious non-geological causes for anomalies in geophysical data • The ability to analyse a geological problem and suggest the most appropriate geophysical solution

Ethical And Social Understanding • As is appropriate in a discipline directly serving the fossil fuel industry, students are encouraged to explore the impacts of this industry on the natural and social environments, and the need for ongoing development of improved and sustainable practices. • Field work indicates the more immediate effects of geophysical acquisition on the local environment, and a sense of respect and care for the natural world is encouraged at all times. • The communal living situation on the field trip provides an invaluable experience of the spirit of courtesy and social responsibility which is essential for the maintenance of human society.

For more information on the University policy on development of graduate attributes in courses, refer to the web http://www.uq.edu.au/hupp/contents/view.asp?s1=3&s2=20&s3=5.



Plagiarism

Below is the University’s definition of plagiarism Plagiarism is the action or practice of taking and using as one’s own the thoughts or writings of another (without acknowledgement). The following practices constitute acts of plagiarism and are a major infringement of the University’s academic values: (a) where paragraphs, sentences, a single sentence or significant part of a sentence which are copied directly, are not enclosed in quotation marks and appropriately footnoted; (b) where direct quotations are not used, but are paraphrased or summarised, and the source of the material is not acknowledged either by footnoting or other simple reference within the text of the paper; (c) where an idea which appears elsewhere in print, film or electronic medium is used or developed without reference being made to the author or the source of that idea. When a student knowingly plagiarises someone’s work, there is intent to gain an advantage and this may constitute misconduct. Students are encouraged to study together and to discuss ideas, but this should not result in students handing in the same or similar assessment work. Do not allow another student to copy your work. While students may discuss approaches to tackling a tutorial problem, care must be taken to submit individual and different answers to the problem. Submitting the same or largely similar answers to an assignment or tutorial problem may constitute misconduct. If a deliberate act of plagiarism is proven,. the results of the assessment may be annulled and other action may be taken as is considered appropriate in the circumstances of the case.

For more information on the University policy on plagiarism, please refer to http://www.uq.edu.au/hupp/contents/view.asp?s1=3&s2=40&s3=12

Supplementary examinations A supplementary examination may be awarded in one course to students who obtain a grade of 2 or 3 in the final semester of their program and require this course to finish their degree. You should check the rules for your degree program for information on the possible award of supplementary examinations. Applications for supplementary examinations must be made to the Director of Studies in the Faculty. EPSA Faculty policy on the award of supplementary exams may be found via the Faculty Guidelines from the EPSA student page http://www.epsa.uq.edu.au/index.html?id=9329&pid=7564

Special examinations If a student is unable to sit a scheduled examination for medical or other adverse reasons, she/he can and should apply for a special examination. Applications made on medical grounds should be accompanied by a medical certificate; those on other grounds must be supported by a personal declaration stating the facts on which the application relies. Applications for special examinations for central and end-of-semester exams must be made through the Student Centre. Applications for special examinations in school exams are made to the course coordinator.

More information on the University’s assessment policy may be found http://www.uq.edu.au/hupp/contents/view.asp?s1=3&s2=30&s3=5 EPSA Faculty policy on the award of special exams may be found via the Faculty Guidelines from the EPSA student page http://www.epsa.uq.edu.au/index.html?id=9329&pid=7564

Feedback on assessment You may request feedback on assessment in this course progressively throughout the semester



from the course coordinator. Feedback on assessment may include discussion, written comments on work, model answers, lists of common mistakes and the like. Students may peruse examinations scripts and obtain feedback on performance in a final examination provided that the request is made within six months of the release of final course results. After a period of six months following the release of results, examination scripts may be destroyed. Information on the University’s policy on access to feedback on assessment may be found at http://www.uq.edu.au/hupp/contents/view.asp?s1=3&s2=30&s3=5 EPSA Faculty policy on assessment feedback and re-marking may be found at http://www.epsa.uq.edu.au/index.html?id=7674&pid=7564

Library contactThe liaison librarian for the physical sciences disciplines is located in the Physical Sciences and Engineering Library in the Hawken Building and may be consulted for assistance in the course:

Gisela [email protected]: 3346 3502

Students with disabilitiesAny student with a disability who may require alternative academic arrangements in the course is encouraged to seek advice at the commencement of the semester from a Disability Adviser at Student Support Services. Assistance for StudentsStudents with English language difficulties should contact the course coordinator or tutors for the course. Students with English language difficulties who require development of their English skills should contact the Institute for Continuing and TESOL Education on extension 56565. The Learning Assistance Unit located in the Relaxation Block in Student Support Services. You may consult learning advisers in the unit to provide assistance with study skills, writing assignments and the like. Individual sessions are available. Student Support Services also offers workshops to assist students. For more information, phone 51704 or on the web http://www.sss.uq.edu.au/index.html. Student Liaison OfficerThe School of Physical Sciences has a Student Liaison Officer as an independent source of advice to assist students with resolving academic difficulties. Contact the school office.


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