Identification the Jakarta Fault using MS-SVD (Multi Scale - Second Vertical Derivatives) Method Gravity Data

Abstract

Jakarta is a metropolitan city in Indonesia with high population. Geologically, its location has the potential to be affected by earthquakes from subduction zones as well as from local faults such as the Cimandiri, Lembang, and Baribis faults. Earthquake history showed that in 1780 and 1834 Jakarta was affected by an earthquake with magnitude Mw 8, destroying existing infrastructure. Several geoscientists believed the source of the fault is located in the south of Jakarta. Study with primary gravity data using the MS-SVD supported by the MS-HDVD method is a good method for identifying faults. From looking at the zero value shift on the MS-SVD graph, a fault zone is visible in the south of Jakarta. It is also confirmed by the CBA map that has contrast gravity between south and north of Jakarta. The faults have parallel-normal and parallel reverse type in East-West direction with dip angle for more than 79°. According to the fault that has been identified, south of Jakarta is evidently crossed by the fault, so the city safety needs to be considered especially for the potential of upcoming natural disasters. However, 2D forward modeling shows that subsurface Jakarta does not have density contrast between rock layers significantly.