Utilization and modeling of satellite gravity data for geohazard assessment in the Yogyakarta area of Java']Java Island, Indonesia

A geohazard assessment was conducted in the Aerotropolis area of the new Yogyakarta international airport, located in the Yogyakarta special region province, Indonesia. The study involved the analysis and modeling of 3-D inversions of earth gravity anomaly data obtained from the high-resolution of Global Gravity Model (GGM). The main objective of the study was to identify subsurface geological structures such as faults, active volcanoes, and sedimentary layers that may pose potential hazards to the Yogyakarta aerotropolis area. The complete Bouguer anomaly in the study region was calculated using modern terrain correction methods that relied on full-scale topography gravity data from the SRTM2gravity model. A 2-D radial spectrum analysis was then performed on this anomaly data, which revealed that the average thickness of sedimentary layers was estimated to be more than 100 m. The rock density contrast was determined using the residual gravity anomaly inversion, which showed a range of-0.086 g/cm3 to 0.043 g/cm3. The analysis of gravity anomalies and rock density contrast provided results that aligned with the regional geological conditions of the Yogyakarta region, including the pattern of igneous rock intrusion with high density contrast, the presence of the Merapi magma chambers associated with low negative density contrast, and the Opak normal fault path at low and high contrast boundaries, which could lead to natural hazards in the region.