High Resolution Dems for Near-Station Terrain Correction in Gravimetry

To obtain a complete Bouguer anomaly it is necessary to apply a terrain correction. This processing step is a critical concern in rugged topography, because the magnitude of the corrections may be large with respect to the anomalies of interest. The problem is particularly important in the application of gravimetry to study volcanic and seismic areas. Normally, the terrain corrections are divided into two parts, one part being the “inner zone”, the zone relatively close to the gravity station, and the other part being the correction for more distant terrain. The latter correction is normally performed using computer routines that access a digital terrain model in form of average elevation data over a regular grid. The corrections for the “inner zone” are generally done manually through the classical template procedures (Hammer, 1939). In the last years it was recognized how the use of automatic procedure to calculate also the inner zone (see e.g., Cogbill, 1990) leads to greater overall accuracy of the total terrain correction at each station due to the possibility to extend this zone to several kilometres from the station. An efficient technique was developed by Loddo and Schiavone (2004).