Geosciences Department - The University of Montana

Gravity and Electromagnetics - Geology 438
Professor: Steve Sheriff
Grading: Based on exams, problem sets, project reports, participation
Spring 2006 - Syllabus
The Summer of Applied Geophysical Experience (Los Alamos National Lab)
The Society of Exploration Geophysics scholarships

Musings, events, and assignments (and a short note on: uncertainty, precision/accuracy, and omitting data)

Spring 2006:

1/23/06: Problems, Mass, moment, gravity (Newton, Maskelyne), and mantle/core
1/25/06: Richter's clock problem, spherical coordinates, more on mass, moment, and density with depth, Press' Monte Carlo approach, equatorial bulge.
1/30: Chauvenet's principle, moment-mass problem, the Earth-Moon system, tidal friction, lunar recession (4.4 +/-0.6 cm/yr),
2/1: International Gravity Formula (gth), the geoid (NGS, PNW, US, world geoid), Free Air and Simple Bouguer Corrections
2/6: Matrix solutions (1, 2), linear density with depth, terrain corrections
2/8: Terrain density, density from FAA, the buried sphere, 2 spheres, interpreting Bouguer anomalies, ambiguity and uniqueness, topography & anomalies, case study: Nyack
2/13: Regional-residual Problem, Bouguer anomalies: Missoula Valley, Northern Rockies, US, regional demo, Missoula Valley(ppt), NE Missoula Valley (Hennes ppt)
2/15: Minnesota (1,2), salt dome, Gauss' theorem, Talwani algorithm, 2D modeling with GravCadW, Swan Valley iterative method
2/20: Presidents (dead) day
2/22: Regional-residual .dat, Drift corrections, self assessment: USGS example, Airy and Pratt (isostacy).
2/27: mountain roots, accomodation space, sedimentary basins (2), P. Birds insights into the regional tectonics of Montana, Crustal thickness (NA, world, histograms), uplift following erosion, Elev/BA profile
3/1: Landscape and erosion, fault scarp erosion, Hudson's Bay (geoid)
3/6: Basic GPS, differential GPS, GPS error (1, 2, 3, 4), PDOP figure, operating the CG3, measuring table height.
3/8: Operating the GPS unit, more gravity measurements
3/13: Problem for today - process and interpret our measurements, gravity flow chart, and gravity assignment.
3/15: Midterm Exam on material through 3/8.
3/20: Flexure of the crust & lithosphere (A.Watt's), Flexure from a periodic load (here's the mathcad document) continued
3/22: elastic thickness from FAA analysis, flexural response function
3/27: Spring Break
3/29: Spring Break
4/3: Flexure from line loads (mcad doc), foreland basins, Purcell Anticlinorium-Sweetgrass Arch system.
4/5: Gravity modeling problems, flexure - numerical solution (Li et al.); Numerical solution from an ice load- NW MT: overall, dip, deformation, deformed contour, GPS-terraces. Self assessment! Animation
4/10: Resistivity (applet, Wenner, Schlumberger, dipole-dipole, compare 'em), values, methods, case studies: water(2), barrier island, landfill, karst, clay, channel, software (Sounder, Res2Dinv)
4/12: Resistivity in the field at the Riverbowl Field (Syscal switch); switch method for psuedosections
4/17: We'll look at your simple Bouguer anomalies, then download & invert resistivity data; Self assessment: resistivity depths, and methods
4/19: Field day.
4/24: GPR introduction, EM waves, GPR applet, moveout, GPR images (1, 2, 3), Noel's moraine, 2-way travel time, synthetic reflections (Excel version), read the case studies from Mala and Sensors & Software
4/26: As a group, take the Syscal resistivity equipment to the field (your choice of venue), structure an experiment that will show something, then collect comparative Wenner and Dipole-Dipole data. Process and interpret those data and give me a joint presentation on the experiment and the results.
51: Electric results in the classroom and radar basics and equipment
5/3: GPR in the field.
5/10 - Gravity presentations and Final (3:20-5:20).

Here's what happened in Spring 2005:

1/24/05: Problems, Mass, moment, gravity - much of it in spherical coordinates, (Newton, Maskelyne, Hutton, Huygens)
1/26: Richter's clock problem, more on density with depth, core-mantle, equatorial bulge.
1/31: Mass-moment problem, the Earth-Moon system, tidal friction, lunar recession (4.4 +/-0.6 cm/yr), International Gravity Formula (gth)
2/2: The geoid (NGS, PNW, US, world geoid), Free Air and Simple Bouguer Corrections, terrain corrections, terrain density, density from FAA, Bouguer anomalies: Missoula Valley, Northern Rockies, US.
2/7: The buried sphere, 2 spheres, interpreting Bouguer anomalies, ambiguity and uniqueness, case study: Nyack, topography & anomalies
2/9: Regional-residual PROBLEM, case studies: Nyack(ppt), Evans-1999, Missoula Valley(ppt), NE Missoula Valley (Hennes ppt), regional demo, Gauss' theorem, Minnesota (1,2),
2/14: Talwani algorithm, 2D modeling with GravCadW, Swan Valley iterative method, Airy and Pratt (isostacy),
2/16: Problems, drift corrections, USGS example, mountain roots, accomodation space, sedimentary basins (2)
2/21: Presidents (dead) day
2/23: P. Birds insights into the regional tectonics of Montana, Crustal thickness (NA, world, histograms), uplift following erosion, Elev/BA profile
2/28: Landscape and erosion, fault scarp erosion, Hudson's Bay (geoid)
3/2: Basic GPS, differential GPS, GPS error (1, 2, 3, 4), PDOP figure, operating the GPS unit, operating the CG3, gravity flow chart, and gravity assignment.
3/7: Midterm Exam (see old exams)
3/9: Field Day!
3/14: Flexure of the crust & lithosphere (A.Watt's)
3/16: Flexure from a periodic load (here's the mathcad document) continued; elastic thickness from FAA analysis, flexural response function
3/21: Spring Break
3/23: Spring Break
3/28: Flexure from line loads (mcad doc), foreland basins, Purcell Anticlinorium-Sweetgrass Arch system. Numerical solution from an ice load- NW MT: overall, dip, deformation, deformed contour, GPS-terraces. Self assessment! Animation
3/30: Terrain corrections (Demo, How to), EM waves, GPR applet, moveout, GPR images (1, 2, 3), Noel's moraine
4/4: Rain, 2-way travel time, synthetic reflections (Excel version), read the case studies from Mala and Sensors & Software
4/6: Demo of GRP, 200 mHz antenna; GPR operation
4/11: More GPR, at the Riverbow Field (50 & 100 mHz)
4/13: GPR Asignment, Field Day!
4/18: Resistivity (Wenner, Schlumberger, dipole-dipole), case studies: water, barrier island, landfill, karst, clay, channel, software (Sounder, Res2Dinv)
4/20: Resistivity at the Riverbowl Field (Syscal switch); Results: EW_line, NS_line.
4/25: Resistivity download, discussion; your gravity presentations
4/27: Another gravity presentation, electromagnetic surveying, case studies: (0, 1, 2, 3, 4).
5/2: The EM31 & operation.
5/4: Your presentations, filtering GPR data.
5/9: Monday - Final Exam,(3:20-5:20; SC 348) Either in class, or the Take Home Exam (your choice but I want to know on Monday, 5/2)

Last Year - Spring 2004:

1/26/04: Problems, mass, moment, gravity - much of it in spherical coordinates, (Newton, Maskelyne, Hutton, Huygens)
1/28: Problems for next Wednesday, more on density with depth, core-mantle, and the Earth-Moon system.
2/2: Richer's pendulum, equatorial bulge, tidal friction, lunar recession (4.4 +/-0.6 cm/yr)
2/4: Problem 2; International Gravity Formula (gth), and the geoid (NGS, PNW, US, world geoid), Free Air and Simple Bouguer Corrections.
2/9: Terrain corrections, terrain density, density from FAA, Bouguer anomalies (Missoula Valley, Northern Rockies, US), and the buried sphere (lunar orbits applet, 3-body.exe (DOS))
2/11: Problems (data), 2 spheres, interpreting Bouguer anomalies, ambiguity and uniqueness, case study-Evans, 1999, Missoula Valley(ppt)
2/16: President's Day
2/18: Regional demo & practice, Gauss' theorem, Minnesota (1,2), the Nyack project (ppt)
2/23: Discuss anomaly separation, NE Missoula Valley (Hennes ppt), Talwani algorithm, 2D modeling with GravCadW, Swan Valley iterative method
2/25: A problem, regional-residual practice, USGS example, topography & anomalies, Airy and Pratt (isostacy),
3/2: Drift corrections, - Jeremy's data: base stations, measuring relative gravity, correcting to known gravity, FAA, sBA
3/4: Terrain corrections (Demo, How to), FAA Basin & Range, what's not Airy supported?, mountain roots, accomodation space, sedimentary basins (2)
3/8: P. Birds insights into the regional tectonics of Montana, Crustal thickness (NA, world, histograms), uplift following erosion, Elev/BA profile
3/10: Landscape and erosion, fault scarp erosion, Hudson's Bay (geoid),
3/15: Problems, sedimentary basin depths, mantle viscosity, backstripping, Elastic thickness
3/17: Puget Sound rebound & tilt, flexure of the crust & lithosphere (A.Watt's)
3/22: Flexure from a periodic load (here's the mathcad document) continued; elastic thickness from FAA analysis, flexural response function
3/24: Time in the bank for field work!
4/5: flexure from line loads (mcad doc), foreland basins, Purcell Anticlinorium-Sweetgrass Arch system
4/7: Basic GPS, differential GPS, GPS error (1, 2, 3, 4), PDOP figure, operating the GPS unit
4/12: Differentially correcting our measurements, gravity flow chart, operating the CG3, measuring furniture heights, and gravity assignment
4/14: Field day - time for your gravity projects; no class.
4/19: Ground Penetrating Radar, GPR demo (250 MHz, shielded antenna) and operation
4/21: Field day - time for your gravity projects; no class.
4/26: GPR near the football stadium. Read the case studies from Mala and Sensors & Software
4/28: EM waves, GPR applet, GPR images (1, 2, 3), resistivity?
5/3: GSA Meeting - go to geophysics talks or work on projects
5/5: GSA Meeting - go to geophysics talks or work on projects
5/12: Our last meeting is 3:10 - 5:20; because it is FINALS WEEK!

The 2004, 2003, and 2002 variants of the course

Previous Exams

Case Studies

Equipment & Procedures:

Read the Gravimeter's Scale	Calculate Drift Corrections	Gravity Flow Chart
Terrain Corrections	GravcadW	PRO-XRS GPS (from Trimble)

Relevant Links:

Earth Coordinate Systems	Geodetic Datums	NGS Geoid Page
GPS Overview	SEG Virtual Museum	Wolfram Resources
Representative textbooks	Society of Environmental and Engineering Geophysics	AGU Reviews of Environmental Geophysics
Environmental Geophysics at Columbia University	Keele University, UK	Boise State - CGISS
Case Studies	Berkely Course Applied Geophysics

Scholarship and summer field experience opportunities:

The Summer of Applied Geophysical Experience supported by Los Alamos National Lab and the Department of Energy.
The SEG (Society of Exploration Geophysicists) scholarship program.

History:

I changed the format for my senior-level geophysics courses in the fall of 2001 (I shuffled Environmental Geophysics with Introduction to Geophysics to spread the field work out over both semesters). Go to the page for the first semester, Seismology and Magnetics, and you'll find links to old exams and problem sets - some are quite relevant to this course.

Free Spreadsheet exercises from Computation and Computer Methods in Geology - you'll need to develop solid spreadsheet skills.

Exercise one covers relative versus absolute addresses and graphing equations.
Exercise two introduces Excel's array functions for transposing, multiplying and inverting matrices.
Exercise three uses the array functions for solving simultaneous equations and fitting lines to linear data.
Exercise four demonstrates Excel's LINEST() function for least squares.
Exercise five requires importing ASCII data, sorting, MEDIAN(), and AVERAGE.

So far the most convenient and expedient way to distribute the information seems to be to provide the material in Adobe's .PDF format. Thus these exercises and notes are provided as .PDF files and you need Adobe's free Acrobat Reader installed in your browser to view them.

If your browser is not currently set up to read and print such files, download Acrobat Reader from Adobe's web page, close your browser (preferably version 4.0 or greater of MS Internet Explorer or Netscape), install the reader, restart your browser, click on one of my links pointing to a set of notes or problems, and Acrobat Reader should pop up with the .PDF file.

Geosciences Department - The University of Montana - 32 Campus Drive #1296 - Missoula, MT 59812-1296
Phone: (406) 243-2341 Fax: (406) 243-4028 Email: geology@mso.umt.edu

The University of Montana Geosciences Department