1. Simple Depth Rules (Half-Width)
Anomaly width contains depth information, but the coefficient depends on source geometry and magnetization.
Concept
- Sharp anomaly = Shallow source.
- Broad anomaly = Deep source.
Current Depth: 5.0 m
2. Peters' Half-Slope Method
A graphical method specifically for dykes using the anomaly slope.
Steps to Calculate:
- Draw a tangent at the point of maximum slope (inflection point).
- Construct a line with exactly half the slope of the tangent.
- Find where this "half-slope" line is tangent to the anomaly curve at two points (one high, one low).
- Measure the horizontal distance 'd' between these two points.
- Apply the formula: Z = d / 1.6
The factor 1.6 is empirical and best suited to thin, steeply dipping, strike-extended sources; treat the result as approximate depth to the top.
3. Reduction to the Pole (RTP)
Correcting the latitude effect to center anomalies over their sources.
Problem & Solution
Problem: At mid-latitudes, induction causes dipoles. The peak is shifted away from the actual source.
Solution (RTP): A mathematical filter simulates measuring the data at the magnetic pole.
Ideal induced-only result: anomalies become more symmetric and centered.
RTP can be unstable at low magnetic inclination and can misplace sources when remanent magnetization is important.
Status: Raw Data