ASSESSMENT OF SPATIAL GEOMETRY OF THE JAVA BACK-ARC THRUST IN WEST JAVA, INDONESIA BASED ON GEOPHYSICAL DATA

The West Java Back-arc (WJBT) in the northern part of the Java area was subjected to numerous magnitudes of seismic events in the Java Back-arc Thrust system, which are genetically related to the well-known subduction of the Australian Plate beneath Java Island, Indonesia. The study aims to identify and model the subsurface structure of the North West Java area where the active fault is found. This work used accessible data, which consists of gravity, seismic reflection, and well data, to provide a wider vision lateral view of the geometry model of the subsurface fault and to delineate the existence of many others in the area under investigation. The gravity data covered the area from north of Bandung to Pamanukan, and seismic and well data was available for the Karawang to Indramayu area. The Bouguer gravity anomaly was used to obtain basin modeling and to analyze density changes for fault identification. The results show interplay with the Bogor Basin Uplifting with the thrusting system in the Java back-arc region. Since seismic activities will play a vital role in the future urban and development strategy in the study area, the fault structure's characteristics should be taken into consideration to mitigate their effects