Abstract

Modern three-dimensional seismic imaging enables a basic geometric description and kinematic interpretation of part of the Fish Creek Slide, a massive (∼4000 km2; 1500 mi2) slope failure beneath Alaska's North Slope. The Fish Creek Slide is divided into a dominantly extensional organized slide zone in the west and a mostly contractional disorganized slide zone in the east. In the organized slide zone, a series of six organized slide blocks detached from the lower slope along steep escarpments during an inferred Albian earthquake focused at depth on a preexisting southeast-striking fault. Blocks were transported eastward into the basin as failure progressed catastrophically yet systematically by northwestward, en echelon, upslope, footwall collapse. During slide evolution, the primary flat detachment switched from the highly radioactive zone down stratigraphic section to the Lower Cretaceous unconformity. Although the seismic interpretation is hampered by a variety of slide-induced signal problems, several significant, previously unrecognized elements of the Fish Creek Slide are described: shear zones related to displacement variations in the slide, duplex structures in the slide blocks, postslide erosional features, and axial structural lows in slide blocks.

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