Geoid and density anomalies



Geoid undulations reflect density contrasts within Earth. In this study we show that many features known from other geophysical sources, such as gravity and magnetic anomaly maps, tectonic and geological maps, are also discernible in an accurate geoid. This suggests an association between these features and density anomalies. To demonstrate the usefulness of the geoid for geophysical interpretation we have chosen to use the “terrestrial contribution” to the UNB Dec. '86 Canadian geoid. This is a high-resolution shorter wavelength (of degree and order higher than 20, or half wavelength less than 1000 km) part, which is readily available as a natural product of the geoid compilation when the UNB formulation of the geodetic boundary value problem is used. To facilitate the recognition of different features we have employed different image enhancement techniques. Hill shading combined with hypsometry (color coding of heights) appears to be the most promising in our context.