Line profiles for a range of situations

Recall that the anomaly pattern recorded over any given target depends upon latitude, target orientation, profile orientation, remanent magnetization of the target, and possible superposition of adjacent targets. To illustrate, here we show the anomaly recorded over two dykes buried at different depths. The dykes are assumed to extend to very great distances into and out of the page (they are 2D targets), and north is to the right (you are looking west), except in figure 3. The sketch to the right illustrates the situtation. The figures below show how data over these dykes will depend on latitude, line orientation, target orientation, and so on. On the graph of the line profile data, note the changes in vertical scale as well as the changes in shape of the graph.

1.	At mid-northern latitudes (45o) the assymetric anomaly has the low end pointing north. Buried dykes are oriented east-west.
2.	At mid-southern latitudes (45o) the anomalous "low" is on the south side.
3.	If buried dykes point north-south so that the survey line runs east-west, the anomaly recorded is very different.
4.	At the magnetic poles, anomalies are symmetric. (Note values for inclination and strike.)
5.	At the magnetic equator, anomalies are also symmetric, but opposite those at the magnetic poles.
6.	If you survey along a line that is at 45o to (rather than perpendicular) the buried 2D target, the anomaly is again very different.
7.	If the shallower body included some remanent magnetization, the anomaly would now consist of the sum of induced and remanent magnetic fields. Compare to example 2., the "normal" anomaly in the southern hemisphere.
	Model earth has two 2D dykes both with susceptiblity k = 15 x 103.