The Brunei slide: A giant submarine landslide on the North West Borneo Margin revealed by 3D seismic data

Three dimensional seismic data, offshore Brunei, provide evidence for a giant landslide with a volume of 1200 km(3), an area of similar to 5300 km(2) and an average thickness of similar to 240 m. It extends for over 120 km from the Baram Canyon in similar to 200 m water depth to the deep basin floor of the North West Borneo Trough. The landslide is a unique example of a major submarine landslide located on a steep, tectonically active margin adjacent to a large river and canyon system. The landslide is mappable using 3D seismic data, which allow detailed imaging of internal flow structures, erosional headwall and the basal sliding surface. The landslide is a complex deposit, involving a chaotic debris flow matrix, with flow structures and blocks 500 to 1000 m wide and up to 250 m thick. Imaging of the basal sliding surface reveals large striations similar to 30-120 km long, similar to 100-600 m wide, and similar to 10-30 m deep that show significant amounts of basal erosion. In the landslide source area we describe fluid escape structures, gas buildups and bottom simulating reflectors, which may provide a mechanism for weakening and triggering slope failure. We also report older landslides, buried several hundred meters beneath the basin floor that indicate giant landsliding is a recurrent process in the NW Borneo Trough. (C) 2007 Elsevier B.V. All rights reserved.