Reconstruction of prehistoric landfall frequencies of catastrophic hurricanes in northwestern Florida from lake sediment records

Sediment cores from Western Lake provide a 7000-yr record of coastal enviro nmental changes and catastrophic hurricane landfalls along the Gulf Coast o f the Florida Panhandle. Using Hurricane Opal as a modern analog, we infer that overwash sand layers occurring near the center of the lake were caused by catastrophic hurricanes of category 4 or 5 intensity. Few catastrophic hurricanes struck the Western Lake area during two quiescent periods 3400-5 000 and 0-1000 C-14 Yr B.P. The landfall probabilities increased dramatical ly to ca. 0.5% per yr during an "hyperactive" period from 1000-3400 C-14 yr B.P., especially in the first millennium A.D. The millennial-scale variabi lity in catastrophic hurricane landfalls along the Gulf Coast is probably c ontrolled by shifts in the position of the jet stream and the Bermuda High. (C) 2000 University of Washington.