Geophysical field methods

Bouguer gravity. The sum of air free correction (elevation correction) and intermediate layer correction Is called Bouguer gravity.



Terrain correction. In the areas with the rigidly-complicated territory it is required to include the special correction, which considers the actual mass distribution between physical surface and sea level. The respective correction is topography (terrain, relief) correction.

The meaning of this correction is as follows: when the observation point is located on the local upland, that is higher surrounding masses, the gravimeter experiences the additional attraction directed down, and the gravimeter countdown will be higher compared to the case when observation point is located at the same elevation, but on the flat surface. On the contrary, when observation point is a local depression that is lower than surrounding mass, the gravimeter experiences additional attraction directed up, and gravimeter countdown will lower than the case when masses surrounding gravimeter would be absent.

Terrain (relief, topography) correction is done through the complex formulas and is required through sufficient information about relief. Inexact value of terrain correction - one of the important reasons, limiting the accuracy of the gravimetric survey, especially in the areas with rigidly-complicated relief.