Paper No. 266-1
Presentation Time: 1:35 PM

LATE HOLOCENE NORTH ATLANTIC HURRICANE ACTIVITY


DONNELLY, J.1, LANE, P.1, VAN HENGSTUM, Peter J.1, HAWKES, Andrea D.2, TOOMEY, Michael Ryan1, RODYSILL, Jessica R.3, and RANASINGHE, Pradeep4, (1) Geology & Geophysics Department, Woods Hole Oceanographic Institution, MS #22, 360 Woods Hole Rd, Woods Hole, MA 02543, jdonnelly@whoi.edu, (2) Geography and Geology, University of North Carolina Wilmington, Wilmington, NC 02543, (3) Geological Sciences, Brown University, 324 Brook Street, Box 1846, Providence, RI 02912, (4) Geological Survey and Mines Bureau, Colombo, 10350, Sri Lanka
With a series of high-resolution reconstructions of hurricane-induced overwash from high deposition rate sites from across the western North Atlantic we document patterns of event occurrence dating back as much as 4500 years. Some sites preserve annual laminations with interbedded overwash sediments that provide exceptional chronological control. The records suggest that while the frequency of hurricane landfall has not changed dramatically, the frequency of intense hurricanes has varied considerably. The sedimentary evidence suggests the eastern seaboard of the United States experienced a period of elevated intense hurricane activity during the 15th, 16th and early 17th Centuries. This interval of increased intense hurricane activity had significant impacts on coastal landforms and ecosystems including more frequent and widespread inlet formation, erosion of coastal wetlands, and forest disturbance. Reconstructions from Puerto Rico, The Bahamas, and southeastern New England indicate another active interval of intense hurricane activity between 2500 and 1000 years ago.

In the 4500-year record of hurricane-induced storm surges from Mullet Pond near Apalachee Bay, Florida, variability in the frequency of the largest storm layers was found to be greater than what would likely occur by chance alone, with intervals of both anomalously high and low storm frequency identified. The frequency of high magnitude events peaked near 6 storms/century between 2700 and 2400 years B1950 and about 4 storms/century about 700 years B1950. The marked decline in the number of large storm deposits, which began around 600 years B1950, has persisted through present with below average frequency over the last 150 years when compared to the preceding 4000 years.

All study sites indicate above average activity between 1500 and 900 years B1950; however, at other times the records are out of phase. This anti-phasing of intense hurricane activity between the East and Gulf coasts is likely not simply a function of changing hurricane tracks given the variability is in the most intense storms. Thus, regional controls on the frequency of intense hurricanes (e.g., loop current penetration in the Gulf of Mexico) likely also have driven spatial variability in Atlantic paleohurricane records.