Simple Forward Calculation Study for Anomaly Response Simulation and Geomagnetic Data Transformation in Karangsambung Area

Abstract

A geomagnetic survey aims to obtain a model related to geological conditions based on the magnetic properties of the rock. Forward modeling techniques can estimate the anomalies that will be observed based on anomalous bodies below the surface. The rectangular prism body forward modeling approach can approximate a complex anomaly body to be a prism group, thus simplifying the computational process of forward modeling. In this research, a program for computing the forward calculation of magnetic data with a rectangular prism approach is arranged. The program is applied to perform forward modeling of the Karangsambung geological conceptual model. Based on the modeling carried out, the magnetic anomaly range in the Karangsambung area was obtained, namely -3200 nT to 2700 nT with the smallest wavelengths based on the simulation results shown in the range of 200 meters. In addition, the forward modeling program is also used to transform geomagnetic data in the Karangsambung area. The transformations applied are the reduction to the poles and the upward continuation transformation by utilizing the equivalent source technique. Based on the transformation result, it can be interpreted that the area of the intrusion rock in Karangsambung is indicated by a magnetic anomaly value of up to 400 nT, While the area of sedimentary rocks, especially the Karangsambung Formation, is shown by a low magnetic anomaly value reaching -400 nT.