Magnetic Anomalies, Marine
Magnetic anomalies are perturbations of the geomagnetic field due to Earth structure. They are seen when one subtracts a regional magnetic field from a series of observed readings. They have a different character over surface of the deep oceans than on they do on land. The unique nature of marine magnetic anomalies became apparent in the early 1950s when submarine detecting magnetometers were used for geophysical exploration by research ships. Over the oceans important marine anomalies may have an amplitude of a few tens to a few hundreds nanotesla and a wavelength of about 100 km, depending upon the depth of water. Previously some geomagnetic field measurements had been made on nonmagnetic ships but these readings were taken so far apart that the short anomalies were not defined. A few aircraft measurements had been made but they were high above the ocean surface reducing the size of the anomaly or were made over the continental shelf where anomalies have a different character from...
- Heirtzler, J.R., LePichon, and Xavier Gregory, B.J., 1966. Magnetic anomalies over the Reykjanes Ridge. Deep‐Sea Research, 13: 427–443.Google Scholar
- Muller, R.D., Roest, W.R., Royer, Y.‐Y., Gahagan, L.M., and Sclater, J.G., 2005. Digital isochrons of the ocean floor. Available at: htto://gdcinfo.agg.nrcan.gc.ca/app/images/agemap.gif
- Vine, F.J., and Matthews, D.H., Magnetic anomalies over oceanic ridges. Nature, 199: 947–949.Google Scholar