Transtensional basins in the Western Sunda Strait

In 1999 a marine geophysical survey collected bathymetric imagery, seismic reflection and refraction data to investigate the crustal structure and evo lution of the Sunda Strait, which is linked to the obliquely convergent geo dynamic setting of the Sumatran trench. The transtensional character of the study area is manifested in faulted blocks of are basement and active norm al faults detected on both sides of a large graben at the western entrance to the Sunda Strait. The combined interpretation of reflection and wide-ang le data reveals over 6 km of sediment graben fill associated with substanti al crustal thinning. The southern part of the study region is only 50 km fr om the trench and the Moho of the downgoing plate is found at a depth of 28 km.