Tom Wilson, Department of Geology and Geography Geol 454 Environmental and Exploration Geophysics I tom.h.wilson Department of Geology and Geography West Virginia University Morgantown, WV Introduction Phone:

Tom Wilson, Department of Geology and Geography Syllabus (see handout) Example paper summary Hunting for Abandoned Wells Hunting for caves General information - handouts

Tom Wilson, Department of Geology and Geography Syllabus (see handout) Textbook (current status ?) Class web page Grading (32% (pbs),28% (labs), 10% (paper summaries), 10% (mid term), 20% (final)) Papers and paper summaries (see handout and link) Hunting for Abandoned Wells Hunting for caves General information

Tom Wilson, Department of Geology and Geography Textbook ?

Tom Wilson, Department of Geology and Geography Geophysics Objectives 1. Obtain conceptual knowledge of the basic theory of gravitational, magnetic, electric, and electromagnetic fields. 2. Develop an understanding of how geophysical observations can be integrated into your discipline or study. 3. Provide analytical experience necessary to oversee applications of these methods in your specialty area.

Tom Wilson, Department of Geology and Geography Geophysics Definitions Applied Geophysics Making and interpreting measurements of physical properties of the earth to determine sub-surface conditions, usually with an economic objective, e.g. discovery of fuel or mineral deposits. Environmental Geophysics The applications of geophysical methods to the investigation of near- surface physico-chemical phenomena which are likely to have (significant) implications for the management of the local environment Sheriff, R. E., Encyclopedic Dictionary of Exploration Geophysics, SEG. & Reynolds (1997)

Tom Wilson, Department of Geology and Geography Geophysical Methods Terrain Conductivity Resistivity Gravity Magnetics These methods represent only a few of the various geophysical methods used to peer beneath the surface in a manner.

Terrain Conductivity Inducing current flow – action at a distance Tom Wilson, Department of Geology and Geography

Terrain Conductivity Instrumentation Active Source Two Commonly used Terrain Conductivity Meters - You’ll hear a lot about these in the first 3-4 weeks of the class EM31 EM34

Tom Wilson, Department of Geology and Geography Multifrequency terrain conductivity meter- Same idea

Applications Tom Wilson, Department of Geology and Geography Metal Detection Contaminant Plumes

Abandoned mine lands and mine spoil Tom Wilson, Department of Geology and Geography

Terrain Conductivity over the Greer Site

Other kinds of instrumentation Gem2 – Aeroquest/GeoPhex Tom Wilson, Department of Geology and Geography

Resistivity Tom Wilson, Department of Geology and Geography Active source Case Histories TerraPlus

Resistivity applications Tom Wilson, Department of Geology and Geography Underground Storage Tanks Leak detectionLeak detection (TerraPlus) WESTEC Case Study Map is contoured in units of 0.5 percent change, which is a measure of the drop in apparent resistivity from the baseline data set to the data collected after 69 gallons of solution was released. The largest observed percent change in the data was 0.2%, concentrated near the northeast margin of the tank, and beneath the center of the tank.

Tom Wilson, Department of Geology and Geography

Landfill Leak Detection A typical response to an introduced leak is shown on in the figure. This calibration demonstrated that the sensitivity of the particular system was approximately 20 gallons in total introduced leachate, and the location ability of the software was within 10 to 20 feet. This 20-gallon detection level is equivalent to a 4-foot-square zone of saturated soil, assuming a 1-foot thickness. Resistivity measurements made below the liner system

Gravitational fields Tom Wilson, Department of Geology and Geography Passive source LaCoste Romberg Gravimeter Worden Gravimeter

Tom Wilson, Department of Geology and Geography x spring extension m s spring mass k Young’s modulus g acceleration due to gravity Colorado School of Mines web sites - Mass and spring Pendulum measurement From Hooke’s Law we get

Newton’s Universal Law of Gravitation Tom Wilson, Department of Geology and Geography Newton.org m1m1 m2m2 r 12 F 12 Force of gravity G Gravitational Constant

We are interested in g object : some subsurface feature like karst systems, bedrock configuration and groundwater accumulations Tom Wilson, Department of Geology and Geography g E represents the acceleration of gravity at a particular point on the earth’s surface. The variation of g across the earth’s surface provides information about the distribution of density contrasts in the subsurface since m =  V (density x volume). m s spring mass m E mass of the earth R E radius of the earth

Tom Wilson, Department of Geology and Geography Comparison of bedrock depth map to the residual gravity map Form Stewart Residual gravity map

Tom Wilson, Department of Geology and Geography Magnetic Methods Passive source Magnetic Elements for your location Today’s Space Weather

Proton Precession Magnetometers Tom Wilson, Department of Geology and Geography Tom Boyd’s Introduction to Geophysical Exploration CourseIntroduction to Geophysical Exploration

See Tom Wilson, Department of Geology and Geography

Field Operation Tom Wilson, Department of Geology and Geography Coal mine refuse area

Magnetic monopoles Tom Wilson, Department of Geology and Geography p1p1 p2p2 r 12 F m12 Magnetic Force  Magnetic Permeability p 1 and p 2 pole strengths Coulomb’s Law

Tom Wilson, Department of Geology and Geography Magnetic Monopoles do not exist. The fundamental magnetic element is a dipole or combination of one positive and one negative magnetic monopole.

Looking for abandoned wells Tom Wilson, Department of Geology and Geography From Martinek Critical to EOR, EGR, CO2 Sequestration, fracking and frack water storage and disposal

Tom Wilson, Department of Geology and Geography 7000 gamma anomaly No excavation planned since the anomaly is located adjacent to a water main From Martinek

Start reading chapter 8 Tom Wilson, Department of Geology and Geography For general background on electromagnetic methods read pages 499 through 514. Most of our work will concentrate on concepts associated with “non-contacting ground conductivity measurements” pages 514 – 518. Visit class page at

Also look over McNeill’s technical note on EM Conductivity/Low induction number Tom Wilson, Department of Geology and Geography Both readings are linked on lecture 1 – see class web page at We will begin discussing basic terrain conductivity theory on Thursday

Any questions? Tom Wilson, Department of Geology and Geography If you are taking the writing section, please remain for a few minutes so we can have a brief discussion and answer any basic questions you may have.

Writing Section – please remain after class Tom Wilson, Department of Geology and Geography Read through the handout with brief question/answer session. Writers should start working on their first paper this week.