The northernmost part of the Great Sumatran Fault map and images derived from gravity anomaly

摘要

The Great Sumatran Fault (GSF) activity is a severe threat to Banda Aceh development as the capital city of Aceh Province, Indonesia. The earthquakes originating along this fault trace, despite generating low strength, considerably threaten infrastructure and human lives. Therefore, a detailed study of the GSF activity and presence becomes critical. In this paper, we applied the Global Gravity Model plus (GGMPlus) to map the subsurface structure and modeling of two GSF segments with a resolution of 200 m/px, namely the Aceh and Seulimeum segments toward the north of the Sumatran Island. The Bouguer anomaly data are inconsistent with the geology of the study areas, dominated by igneous rocks on the Aceh segment and volcanic rocks on the Seulimeum segment. Further, the contrast between the Seulimeum segment in the northeast and the Aceh segment in the southwest can be demonstrated by high-pass filtering. The GGMPlus data validation results with field measurements using the Scintrex CG-5 Autograv, the root mean square error obtained via data comparison are 12.32% in the Krueng Raya fault zone, and 26.1% at the Seulawah Agam Volcano area, respectively. We also performed 2D gravity data modeling along with the Aceh and Seulimeum segments in the NW–SE direction. This model was then compared with the geological cross section, seismicity, and magnetotelluric data. The results of Singular Value Decomposition and Occam inversion show three vertical blocks of high densities with an interspersion of lower densities, which can be confirmed as the Aceh and Seulimeum segments. Based on data processing, it can be concluded that the GGMPlus satellite can improve the maps and images of the northernmost GSF structure.