The outcome of geological mapping alone might be though of as a view of the rocks at or near the surface. It is very often important - especially in resource investigations - to have a quantified, three-dimensional view of the surface. It is this capability which makes Geophysics important.

This segment

•  looks at application of geophysics to geological mapping

Main objective

to enable the eventual integration of geophysical data with other geological data.

• Describe physical basis
• Discuss simple theory
• Show responses
• Case history

Geophysics is

"The use of observations of physical phenomena to infer the structure of the Earth."

Geophysics uses

the effects of differences in physical properties of rocks of different kinds.

allow "remote sensing" of rocks below the surface, by measuring these physical fields.
Fields are usually measured at the surface, but give rise to a third-dimensional view.

• We can usually predict the response of a "standard" Earth
• Anomalies are differences between observation and expectation
• Anomalies result from differences in rock properties

Calculations are needed, to

• predict background response
• predict response of inferred structures

The maths can be very heavy, but
There are many simple short cuts.

Gravity
Simple physics, wide application, simple calculations
Magnetics
Very wide application, more complicated physics, qualitative approach (here)
Electrical Methods
Range of methods, applications, usually for specific purposes
Seismic Methods
Simple physics, important applications

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