2500-year paleotempestological record of intense storms for the northern Gulf of Mexico, United States

Abstract

The northern Gulf of Mexico has been devastated by recent intense storms. Camille (1969) and Katrina (2005) are two notable hurricanes that made landfall in nearly the same location in Mississippi. Fully understanding the risks and processes associated with hurricane impacts are impeded by a short and fragmented instrumental record, however. Paleotempestology has the potential to employ modern analogues from intense storms in this region to extend the hurricane record beyond pre-observational time. Existing empirically-based models can back-calculate surge heights over coastal systems as a function of transport distance, particle settling velocity, and gravitational acceleration. We collected sediment cores in a pond (3) and adjacent beach (1) in Hancock County, Mississippi. Grain-size, loss-on-ignition, and microfossil analyses were conducted on cores in the context of a Bayesian statistical age model using 137Cs and 14C dating. Using Hurricane Camille to calibrate the archive, similar coarse-grained deposits were identified, and inverse sediment transport models calculated paleosurge intensities similar in magnitude to Camille over the 2500-yr record. Our multi-millennial annual average landfall probability (0.48%) closely matches previously published studies from the Gulf of Mexico, indicating that intense hurricanes have not varied over these timescales. Over centennial timescales, active intervals occurred between 900 to 600 and 2200 to 1900yr BP, with relative quiescence between 1900 to 900yr BP. Comparisons with other published sites support the notion that southerly shifts in the Loop Current may be responsible for the decline in activity around 600yr BP.