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Gravity
and Electromagnetics - Geology 438
Professor: Steve
Sheriff
Grading: Based on exams,
problem sets, project reports,
participation
Spring 2004 - Syllabus
The Summer of Applied Geophysical
Experience (Los Alamos National Lab)
The Society
of Exploration Geophysics scholarships
-
- 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:PNW
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!
-
- 1/29: A couple
problems for
next week, more on moment, and the Earth-Moon
system.
- 2/3: Tidal
friction, lunar
recession, International
Gravity Formula (gth), and the geoid
(PNW, US,
world geoid)
- 2/5: Solver
and solving problems, spherical
trig, Free Air anomalies, Bouguer
anomalies, terrain density,
density from FAA,Terrain
corrections
- 2/10: Buried
sphere (& 2 spheres),
interpreting Bouguer anomalies, ambiguity and uniqueness, Gauss' theorem
- 2/12: Problems
(data),
Gauss continued, (US Bouguer map,regional
and residual (Figure 1,
2), case study-Evans,
1999, Missoula Valley(ppt)
- 2/17: President's
Day
- 2/19: Regional
- practice, Minnesota
(1,2),
the Nyack project (ppt),
Talwani algorithm, 2D modeling
with GravCadW,
basin inversion.
- 2/24: A problem
of gravity, NE Missoula Valley (Hennes ppt),
Montana's ranges & Tertiary
Basins, sampling,
topography & anomalies
and a start on Airy and Pratt
(isostacy).
- 2/26: Isostacy,
mountain roots, accomodation
space, sedimentary
basins, and P.
Birds insights into the regional tectonics of Montana
- 3/3: Crustal
thickness
(NA, world,
histograms),
uplift following erosion,
Elev/BA profile,
landscape erosion,
- 3/5: Problems
for Monday!, Hudson's Bay
(geoid), mantle viscosity,
backstripping
- 3/10: Elastic
thickness, flexure of the crust & lithosphere (A.Watt's)
- 3/12:
Midterm Exam -
want to see the 2002 midterm?,
older exams?
- 3/17: Flexural
equation, flexure from a periodic
load (here's the mathcad
document), elastic thickness from FAA analysis
- 3/19: Fourier
analysis, convolution,
flexure from line loads
(mcad doc),
foreland basins
- 3/31: Results
of end loads - some basin questions.
- 4/2: Basic
GPS,
differential
GPS, GPS error (1,
2,
3,
4),
PDOP
figure, operating the CG3,
and measuring
furniture heights
- 4/7: Gravity
drift corrections, and operating
the GPS
unit.
- 4/9: Differentially
correcting our
measurements, and the gravity
assignment
- 4/14: Class
time dedicated to gravity surveys and consultation (stop by)
- 4/16: Progress
reports, EM
waves, and Ground Penetrating Radar; GPR basics, GPR demo and
operation,
GPR applet
- 4/21: GPR
assignment, gravity progress reports, GPR images (1,
2, 3),
applications (Mala, Sensors
& Software),
- 4/23: No class
- Field Day
- 4/28: Simple
Bouguer anomaly maps due, know your quadrangle (USGS),
and terrain corrections
- 4/30: Basics
of EM, in-phase & quadrature (fig. 1,
2) signals, EM31
case studies,
and electrical resistivity methods.
- 5/5: EM-31,
or resistivity, or rain?
- 5/7: Take
home final, resistivity at Riverbowl Field
- 5/12: The
Final Exam time! 3:20 - 5:20, Monday the 12th:
Presentations/discussions on your work.
The 2002
variant of the course.
Previous
Exams
Case
Studies
Equipment
& Procedures:
Scholarship
and summer field experience opportunities:
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.
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