Abstract

The outer continental shelf off southern Virginia and North Carolina might be in the initial stages of large-scale slope failure. A system of en echelon cracks, resembling small-offset normal faults, has been discovered along the outer shelf edge. Swath bathymetric data indicate that about 50 m of down-to-the-east (basinward) normal slip has occurred on these features. From a societal perspective, we need to evaluate the degree of tsunami hazard that might be posed by a major submarine landslide, such as the nearby late Pleistocene Albemarle-Currituck slide, if it nucleated on the newly discovered crack system. Toward this goal, a tsunami scenario is constructed for the nearby coastal zone based on the estimated volume and nature of the potential slide. Although a maximum tsunami height of a few to several meters is predicted, the actual extent of flooding would depend on the tidal state at the time of tsunami arrival as well as the details of the hinterland topography. The Virginia–North Carolina coastline and lower Chesapeake Bay would be most at risk, being nearby, low lying, and in a direction opposite to potential slide motion.

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