The Digital Magnetic Anomaly Map of the World

WDMAM

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The Digital Magnetic Anomaly Map of the World (WDMAM) results from an international effort to build the first global compilation of the wealth of magnetic anomaly information derived from more than 50 years of aeromagnetic surveys over land areas, research vessel magnetometer traverses at sea, and observations from earth-orbiting satellites, supplemented by anomaly values derived from oceanic crustal ages. The objective is to provide an interpretive dimension to surface observations of the Earth's composition and geologic structure. The magnetic anomalies represented on this map originate primarily in igneous and metamorphic rocks, in the Eart's crust and possibly, uppermost mantle. Magnetic anomalies represent an estimate of the short-wavelength (<2600 km) fields associated with these parts of the Earth, after estimates of fields from other sources have been subtracted from the measured field magnitude. The natural increase of temperature with depth in the Earth means that rocks below a certain depth, termed the Curie depth, will be essentially non-magnetic. This depth is typically in excess of 20 km in stable continental regions, and may be as shallow as 2 km in young oceanic regions. Studies of crustal magnetism have contributed to geodynamic models of the lithosphere, geologic mapping, and natural resource exploration. Inferences from crustal magnetic field maps such as these, interpreted in conjunction with other information, can help delineate geologic provinces, locate impact structures, dikes, faults, and other geologic entities which have a magnetic contrast with their surroundings. To this end, the World Digital Magnetic Anomaly Map (WDMAM) is available in both digital and map form at CGMW and GTK.

Map of the total intensity magnetic anomaly map derived from a compilation of aeromagnetic and marine magnetic data. Are left in blanc the area where no data are available.
Total intensity magnetic anomaly map derived from a compilation of aeromagnetic and marine magnetic data. Are left in blanc the area where no data are available.

The GFZ has been involved in the compilation of this map and has built its own version of the map that can be downloaded from GTK. As for the official map, the anomaly field is shown at an altitude of 5 km above the WGS84 ellipsoid. The magnetic fields shown are designed to be internally consistent over the measurement domain, extending from the surface to satellite altitude.

Kontakt

Profilfoto von  Dr. Monika Korte

Dr. Monika Korte
Geomagnetismus

Behlertstraße 3a
Haus K 3, Raum 116
14467 Potsdam
Tel. +49 331 288-1268