Bouguer anomaly
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In geodesy and geophysics, the Bouguer anomaly is computed from a free-air anomaly by computationally removing from it the attraction of the terrain, the Bouguer reduction.
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Nj_cboug.jpg
Nj_cboug.jpg
Bouguer anomaly map of the state of New Jersey (USGS)
In case the terrain attraction is removed precisely, we speak of a refined Bouguer reduction. In case the terrain is approximated by a flat plate of thickness <math>H<math>, the height of the gravity measurement location above sea level, we speak of a simple Bouguer reduction. The difference between the two, the differential gravitational effect of the unevenness of the terrain, is called the terrain effect. It is always negative.
External link
- Bouguer anomalies of Belgium. The blue regions are related to deficit masses in the subsurface (http://www.astro.oma.be/D1/GRAVIMETRY/gravboug.html)