Perhitungan Anomali Full Tensor Gradient dari Anomali Bouguer dengan Transformasi Fourier menggunakan Bahasa Pemrograman Python

Abstract

Full Tensor Gradient (FTG) is the first-order derivative of all gravity vector components (gx, gy, gz) in the x, y, and z directions, which return 6 unique tensors gradient. The advantage of gradient anomaly calculation on potential field data in both vertical and horizontal directions could describe the subsurface conditions, especially in delineating the anomalous body. On the other hand, Bouguer anomaly data that is usually obtained from field measurements are gravity anomaly on the vertical component (gz) only, while gravity anomaly data on the horizontal component (gx, gy) are rarely found. In this study, the authors present the FTG calculations using Fourier transform on complete Bouguer anomaly data and synthetic data was obtained from the forward modeling of 3D mesh grid models where the source of anomaly was built in the form of simple geometry such as prisms and spheres. Based on the results of FTG calculations, it is obtained that the gxx and gyy tensor anomaly enhance the edges of the source of anomaly on the x dan y axes, meanwhile the gzz tensor anomaly can improve the response of anomalous objects on all edges parallel to the horizontal axis. Furthermore, the gxz and gyz tensor anomaly indicate the presence of symmetry that passes through the center of mass of the anomalous body. The results of this study denote that FTG can be calculated from Bouguer anomaly (gz) and the anomaly of various tensor components are able to enhance the response of the anomalous body.