TOPOGRAPHIC REDUCTION OF GRAVITY MEASUREMENTS BY NUMERICAL INTEGRATION OF BOUNDARY INTEGRALS*

A numerical method for calculating the topographic reduction of gravity measurements is developed which follows the approximation of the topography by a single valued function. The method involves the conversion of the volume integral for the gravity effect into a two-dimensional definite integral. The definite integral is partly solved by explicit, and partly by numerical, integration, using the Gauss-Legendre quadrature formula. This method is well suited to calculating the topographic reduction of 50 to approximately 1000 m from the station–especially for microgravimetric surveys in areas of steeply sloping terrain. To test the method in practice it was applied in an area of rough relief in Keban (East Turkey).