The Correlation of Land Survey and Satellite Gravity Data. Study Case: Timor Leste Area

Abstract

The gravity method has been widely used in tectonic studies and the determination of geological structures. Besides land surveys, gravity data can also be measured by using satellites. However, the gravity data obtained from the satellite is usually not as good as the land survey. For example, the satellite data provided by Topex has a resolution of 1-minute grids, while the land survey could have a higher resolution. It means the gravity data obtained from the satellite cannot be as detailed as the land survey. To understand the relationship between both data, we calculate the correlation on the CBA, regional, and residual map. We also compared the maps qualitatively with geological data. During our investigation in the Timor Leste area, it was found that the correlation value between the CBA, regional, and residual from both data (land survey and satellite) is 0.703, 0.722, and 0.015 sequentially. The CBA and regional of both gravity data have the best agreement, but the residual nearly doesn’t have any correlation. This result is because the satellite data has 1-minute grids in resolution, which means the spacing between the gravity data is roughly about 1800 m. With that spacing, the full wavelength that can be observed is more than 3600 m, so anomalies in lower wavelengths usually associated with shallow depths are not good enough to be appropriately measured. Vice versa, the longer wavelengths will be sufficiently provided by satellite. The long-wavelength of gravity data has considerable potential to be used in investigating regional anomalies, such as basement and general geologic mapping. Our results also show that the regional gravity anomaly has high compatibility with geological data.