Plate boundary reorganization in the active Banda Arc–continent collision: Insights from new GPS measurements

Abstract: New GPS measurements reveal that large sections of the SE Asian Plate are progressively accreting to the edge of the Australian continent by distribution of strain away from the deformation front to forearc and backarc plate boundary segments. The study was designed to investigate relative motions across suspected plate boundary segments in the transition from subduction to collision. The oblique nature of the collision provides a way to quantify the spatial and temporal distribution of strain from the deformation front to the back arc. The 12 sites we measured from Bali to Timor included some from an earlier study and 7 additional stations, which extended the epoch of observation to ten years at many sites. The resulting GPS velocity field delineates at least three Sunda Arc–forearc regions around 500 km in strike-length that shows different amounts of coupling to the Australian Plate. Movement of these regions relative to SE Asia increases from 21% to 41% to 63% eastward toward the most advanced stages of collision. The regions are bounded by the deformation front to the south, the Flores–Wetar backarc thrust system to the north, and poorly defined structures on the sides. The suture zone between the NW Australian continental margin and the Sunda–Banda Arcs is still evolving with more than 20 mm/yr of movement measured across the Timor Trough deformation front between Timor and Australia. [Copyright &y& Elsevier]