GEOMORPHOLOGY OF THE JAVA FOREARC BASIN, INDONESIA

This paper focuses on the western Java fore-arc basin, close to the Sunda Strait. The Indo-Australian Plate is subducted beneath the Eurasian Plate with an average speed of 6.7 cm/yr in a north-easterly direction. In the region of the Sunda Strait frontal convergence in front of Java changes to oblique convergence in front of Sumatra. This transition leads to the evolution of huge strike-slip faults like the Sumatra Fault Zone and the Mentawai Fault Zone. In the studied area these major two fault zones join at the continental slope. Additional, in front of Java other strike-slip fault systems like the Ujung Kulon Fracture Zone, the Pelabuhan Ratu Fault Zone and the Cimanderi Fault zone are involved.

Bathymetric grids have been calculated from bathymetric data obtained during German Sonne Cruises SO137 and SO138 and Japaneses cruise Yukosuka yk0102, yk0207. The Sonne cruises were a cooperation between Germany and Indonesia. During cruise SO137 multi-channel-seismic reflection profiles of 4100km length were jointed by HydroSweep data. In addition, sediment echosounding, magnetic and gravimetric measurements were carried out. During SO138 ocean bottom hydrophones and ocean bottom seismometers were deployed along 9 profiles with a total length of 1860km. In addition, magnetic, gravimetric and bathymetric data were collected.

At present we perform a fault system analyses on the basis of bathymetric and seismic data of the Sunda Strait region. Morphological interpretation is done in Arc Gis. Different fault directions are mapped and displayed in rose diagrams. Deformation features will be interpreted. IVS 3D Fledermaus will be used to show 3D view of the fault systems. IESX, a seismic interpretation tool of GeoFrame, is used to analyse different fault systems along 2-D cross sections.