Regional Gravity Terrain Corrections: examples from South Australia

Abstract

Traditional Bouguer corrections assume that the Earth behaves as a flat slab (Bouguer reduction), an assumption that is incorrect. A more accurate method of removing the effects of an Earth model is to take into account the terrain information, and assume a curved Earth. Terrain corrections are becoming more commonplace in individual surveys as computer power increases. We have produced a regional (state-wide) scale terrain corrected gravity grid, using a 1-second DEM to calculate the correction. The correction adds a subtle change to the state wide gravity, removing some regional lows. It can be used as a simple visual tool to determine where terrain corrections are more appropriately undertaken.