Detection and Identification of North-South Trending Magnetic Structures Near the Magnetic Equator
European Association of Geoscientists and Engineers, Geophysical Prospecting, 2000. Presented at the 61st EAGE Conference — Geophysical Division, Helsinki, Finland, June 1999.
Les P. Beard*, Geological Survey of Norway
Paper – [pdf] MagStructures_near_magnetic_equator_GeopProsp_LPB_2000.
Long, structurally undeformed north-south trending structures show no magnetic anomaly at the magnetic equator, except at the north and south truncations of the structure. However, folding, faulting, differential erosion or other structural deformation can produce detectable magnetic anomalies in equatorial structure. Spatial variation in magnetic susceptibility or remanent magnetization can also produce anomalies in equatorial north-south structures.
The anomaly patterns are often more complicated than patterns produced by similar structures at high latitudes, but interpretational insight can be gained through numerical modelling of common structures. Reduction-to-pole and analytic signal filters can aid in interpretation of equatorial anomalies, but these must be applied carefully because of instabilities deriving from filter design and noise amplification.