1997-99 Catalog Data : GE381: Gravity and Magnetic Interpretation Methods (0-3-0) f. 3 credits.
Interpretation of magnetic and gravitational anomalies based on geologic modeling, including basic filter theory and space filtering of geophysical data to separate anomalies. Particular emphasis is on the design of methods to solve interpretational problems related to geological structures. Prerequisites: PH205; GE304 or CE304; and GE233 or equivalent; or permission of instructor.

Textbook: None.

Coordinator: Jimmy F. Diehl, Professor.

Prerequisites by Topic: General Physics II; Introduction to Field Geophysics; Structural Geology I.

Course Objectives:
Objective 1: To teach the student how to use forward modelling techniques to interpret gravity and magnetic anomalies assuming simple geometric shapes for the causative bodies, how to do more complex 2D gravity modelling, and how to calculate excess mass.
Objective 2: To demonstrate the rudiments of filtering to enhance gravity and magnetic anomalies.
Objective 3: To develop the student's ability to design a gravity/magnetics survey, costing the survey, conduct the survey and interpret results.

Topics:
1. Introduction and review
2. Potential field equations
3. Gravity
Regional-residual separation
Gravity effects of geometric shapes
Excess mass calculations
Gravity effects of complex shapes
Gravity anomaly maps
4. Magnetics
Magnetic anomaly sketching
Magnetic effects of geometric shapes
Slope/half slope methods
Other depth estimators
Magnetic effects of complex shapes
Magnetic anomaly maps
5. Filtering
Convolution and data smoothing
Fourier series
Anomaly separation and enhancement

Course Content: 2 credits of Engineering Design and 1 credit of Engineering Science

Course Performance Criteria:

Course Objective 1:
Performance Criteria
1.1 Students will demonstrate an ability to calculate the gravitational effects of simple geometric shapes and more complex shapes, modify the shapes until a satisfactory fit is obtained with the observed anomaly, and apply a geological interpretation to their model. They will also demonstrate the ability to calculate excess mass and the total mass responsible for an observed anomaly. [contributes to attainment of outcomes a, l, m, r, x, bb]

Course Objective 2:
Performance Criteria
2.1 Students will understand the basic concepts of spatial filtering to enhance gravity and magnetic anomaly maps. [contributes to attainment of outcomes a, l, m, bb]

Course Objective 3:
Performance Criteria
3.1 Students will be able to plan, cost, carry out, and interpret results of a gravity or magnetic survey. [contributes to attainment of outcomes b, g, k, z]

Prepared by: Jimmy F. Diehl
Date: 9-March-98