ACTIVE FAULTING COINCIDENT WITH THE CAPE FEAR SLIDE HEADWALL: IMPLICATIONS FOR SLOPE STABILITY AND TSUNAMIS ALONG THE U.S. EAST COAST

The Cape Fear slide, the largest known submarine landslide on the U.S. Atlantic Continental Margin, is a recent (~20 ka) mass-wasting event that generated potentially large tsunamis. Previous studies suggest that gas-hydrates, ocean currents, and salt tectonics played a role in slide triggering, however, the exact cause of the slide and the probability of future slides in this region remains unclear. Here, analyzing recently collected high-resolution multibeam and chirp data, we create the highest resolution bathymetric and subsurface images yet of the Cape Fear Slide, and from this, constrain the shallow structure of the region. With these data, we identify a single massive normal fault that intersects the main Cape Fear Slide headwall and suggest that slide failure initiated along this fault. Our analysis clearly indicates that this fault is active and that slide failure may likely occur again along the fault. The fault strikes parallel to a linear chain of salt diapirs and extends ~100 km south of the Cape Fear Slide. We suggest that ongoing salt intrusion activates this fault and augments slope instability in the region. Using a hydrodynamic model we developed to predict the size of ocean-waves generated by the main Cape Fear Slide, we show that such mass wasting events create large tsunamis that could significantly impact the US coast.