The large waves generated by Hurricane Ivan caused extensive damage to the offshore oil industry and to the coastal areas on the Gulf of Mexico. This damage and the wave conditions have received considerable media coverage. There has been speculation that the associated wave conditions correspond to a 1000-year event and that the criteria for designing offshore structures in the Gulf of Mexico may need revision. In view of what appear to be extraordinary wave conditions, we analyzed all of the measurements from National Data Buoy Center (NDBC) buoys in the Gulf of Mexico and elsewhere in U.S. waters in order to place Hurricane Ivan's waves in the context of other measurements. It was found that the maximum significant wave height (SWH) measured during Hurricane Ivan in the Gulf of Mexico exceeded the largest wave heights ever recorded in all U.S. waters, even though on a return period basis, the Gulf of Mexico has the smallest wave climate compared with all other regions around the United States. At four locations in the Gulf of Mexico, the SWHs were the largest ever recorded at those locations, and exceeded the previous biggest waves by a significant margin. Nominal wave-induced velocities are estimated to be as high as 3.5 m s−1 at some locations, no doubt contributing to the extensive mud, sediment, and pipeline movements that have been reported. Calculations based on the admittedly short-duration datasets suggest that some SWHs measured during Hurricane Ivan correspond to recurrence intervals on the order of several thousand years.
Department of Maritime Systems Engineering, Texas A&M University at Galveston, Galveston, Texas