**7. Methodology**

The target of the gravity method is the determination of important facts about the earth's subsurface. One can just study the grid of gravity values for the determination of the lateral location of any gravity variations or perform a more thorough analysis to calculate the nature (depth, geometry, density) of the subsurface structure that caused the gravity variations. To determine the latter, it is usually necessary to distinguish the anomaly of interest (residual) from the remaining background anomaly (regional).

Gravity data were analyzed and interpreted using the second vertical derivative method. Performance of horizontal and vertical derivatives was evaluated using synthetic data. SVD calculation using 2D was applied to identify fault structure. The first derivatives of the horizontal component (dg/dx and dg/dy) were calculated in the excel software. Then, the second derivatives (*<sup>∂</sup>*2g *<sup>∂</sup>*x2 and *<sup>∂</sup>*2g *<sup>∂</sup>*y2) were calculated in the same software.

These are used to find the second vertical derivative (*<sup>∂</sup>*2g *<sup>∂</sup>*z2 ) using relations in Laplace's equation as mentioned in Eq. (12). The second vertical derivative values are then gridded in surfer software. The grids are then used to plot the contour map known as the SVD map in **Figure 3**.

The second vertical derivative map is expected to remove the effect of regional trends. The edge of the residual anomaly was then observed, which is seen on zero contours. This will help to predict the anomaly in the map with its position.
