Intense Hurricane Activity Over the Past 1500 Years at South Andros Island, The Bahamas

Abstract

Hurricanes cause substantial loss of life and resources in coastal areas. Unfortunately, historical hurricane records are too short and incomplete to capture hurricane-climate interactions on multi-decadal and longer timescales. Coarse-grained, hurricane-induced deposits preserved in blue holes in the Caribbean can provide records of past hurricane activity extending back thousands of years. Here we present a high resolution record of intense hurricane events over the past 1500 years from a blue hole on South Andros Island on the Great Bahama Bank. This record is corroborated by shorter reconstructions from cores collected at two nearby blue holes. The record contains coarse-grained event deposits attributable to known historical hurricane strikes within age uncertainties. Over the past 1500 years, South Andros shows evidence of four active periods of hurricane activity. None of these active intervals occurred in the past 163 years. We suggest that Intertropical Convergence Zone position modulates hurricane activity on the island based on a correlation with Cariaco Basin titanium concentrations. An anomalous gap in activity on South Andros Island in the early 13th century corresponds to a period of increased volcanism. The patterns of hurricane activity reconstructed from South Andros Island closely match those from the northeastern Gulf of Mexico but are anti-phased with records from New England. We suggest that either changes in local environmental conditions (e.g., SSTs) or a northeastward shift in storm tracks can account for the increased activity in the western North Atlantic when the Gulf of Mexico and southeastern Caribbean are less active.

Revising evidence of hurricane strikes on Abaco Island (The Bahamas) over the last 700 years

“…When there was more than one event in a blue hole record falling within the age uncertainties of an event from another blue hole record, we consolidated the event in the first blue hole site that was closest in age to that captured in the second site. The main difference between the new South Andros stack presented here and the solitary paleo record from blue hole AM4 featured by Wallace et al 25 is a period of increased activity in the stacked record from ~ 1600 to 1780 CE.…”

“…The methods of to identify the most likely intervals (i.e., event beds) where coarse-grained sedimentation substantially exceeds background sedimentary conditions were modified from Donnelly, et al 18 , Wallace, et al 25 , Lane et al 27 . First, an 11-point moving average of data excluding those with a coarse fraction value > 12% (upper 90th percentile of %D >63 µm ) was subtracted from all %D >63 µm data to establish a series of coarse sediment anomalies (CSA).…”

“…Values for expected hurricane event frequency (λ) were based on a regional estimate calculated by Wallace, et al 25 (regional bounding 550 km radius circle centered over 24.08°N and 75.39°W). The expected regional frequency value (λ) of ≥ category 2 hurricanes passing within 50 km of any given point is 3.7 events per century, resulting in upper 90th percentile cutoff threshold of 7.3 events per century and a lower 10th percentile cutoff threshold of 1.6 events per century.…”

1600 year-long sedimentary record of tsunamis and hurricanes in the Lesser Antilles (Scrub Island, Anguilla)

“…Sedimentary studies along the coasts of various islands and in lagoons have revealed deposits related to past hurricanes (Donnelly and Woodruff, 2007;McCloskey and Keller, 2009;Malaizé et al, 2011;Donnelly et al, 2015;Denommee et al, 2015;Wallace et al, 2019), but no paleotempestology studies have been conducted in Anguilla or Scrub Island.…”

“…Scrub Island sediment record brings new knowledge about variations in past hurricane activity in the Caribbean. Thus we compared this new chronicle to other sites where hurricane sediment records are available: A/ Salt Pond, Massachusetts (Donnelly et al, 2015), B/ South Andros, Bahamas (Wallace et al, 2019), C/ Lighthouse Reef blue hole, Belize (Denommee et al, 2015) (Fig. 9A, B, C).…”