Year: 2023 | Month: September | Volume: 10 | Issue: 9 | Pages: 271-280
DOI: https://doi.org/10.52403/ijrr.20230929
Semarang Subsurface Model Using Airborne Gravity Data
Popy Dwi Indriyani1, Rina Dwi Indriana2, La Ode M. Sabri3, Arisuna Pahlevi4
1Post Graduate Student of Physics Department, Diponegoro University, Indonesia
2Physics Department, Faculty of Sains and Mathematics, Diponegoro University, Indonesia
3Geodesy Engineering Department, Faculty of Technic, Diponegoro University, Indonesia
4Center for Geodetic Control Network and Geodynamica, Geospatial information agency
Corresponding Author: Rina Dwi Indriana
ABSTRACT
The city of Semarang faults became active again in the Quaternary era. The gravity method has been widely used to identify subsurface conditions in Semarang City and its surroundings, especially the satellite gravity method and land gravity methods. Meanwhile, Semarang City and its surroundings have never used the airborne gravity method. Therefore, this study aims to identify subsurface conditions, especially faults, using airborne gravity data in Semarang and its surroundings. The airborne gravity value is the gravity value at a certain height. Therefore, in this study, the downward continuation process using Molodensky methods on airborne gravity data is useful for obtaining gravity values at topographical heights. Based on the residual anomaly map, there is a low gravity anomaly with a value range of -6.6 – (-0.5) mGal, located between high gravity anomalies, which have a value range of 1.7-7.4 mGal, which is suspected to be associated with a shallow structure in the form of a fault in the research area. Based on the residual anomaly map, the subsurface 2D model uses a forward model in areas identified as faults on the geological map. The model results have an error value of 0.221, representing a fit model that shows a picture of subsurface conditions close to the actual situation with fault structures on the D-D' Line.
Keywords: Airborne gravity, fault, downward continuation, Molodensky method
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