High sea-floor stress induced by extreme hurricane waves

[1] Strong surface waves and currents generated by major hurricanes can produce extreme forces at the seabed that scour the seafloor and cause massive underwater mudslides. Our understanding of these forces is poor due to lack of concurrent measurements of waves and currents under these storms. Using unique observations collected during the passage of a category-4 hurricane, Ivan, bottom stress due to currents and waves over the outer continental shelf in the Gulf of Mexico was examined. During the passage of Ivan, the bottom stress was highly correlated with the wind with a maximum of about 40% of the wind stress. The bottom stress was dominated by the wave-induced stresses, and exceeded critical levels at depths as large as 90 m. Surprisingly, the bottom damaging stress persisted after the passage of Ivan for about a week, and was modulated by near-inertial waves.