SCINTREX ENVI-MAG User Manual

Applications
B1-14 ENVI-MAG Manual
Figure B-13 Orientation and anomaly amplitude - a) Positive, b) negative and
c) null anomalies.
In case a), the projection is in the same direction as the undisturbed total field,
resulting in a positive anomaly. In case b), the direction is opposite to the undis-
turbed total field, resulting in a negative anomaly. In case c), however, the direc-
tion happens to be perpendicular to the undisturbed total field, resulting in no
anomaly at all.
Case c) is the most interesting because even though an anomaly exists, it cannot
be measured. You may want to keep this in mind when carrying out a magneto-
meter survey for buried drums, pipelines or metal sheets.
These are only simplified examples. Some situations, for instance a collection of
drums, each having it’s own orientation and intensity for the local disturbance
vector, will possibly exhibit a very complex anomaly vector. When this is added
to the Earth’s magnetic field and then measured only as the scalar amplitude, the
results may not be exactly as expected.
a
b
c

SCINTREX ENVI-MAG Specifications

General

Brand	SCINTREX
Model	ENVI-MAG
Category	Measuring Instruments
Language	English