18-8 Hurricane Joaquin, October 2015: A 10-Year Retrospective on Consequences of an Extreme Weather Event on San Salvador Island, The Bahamas

Session: Shaping a Sustainable Future with Geology in the Twenty-First Century: Geology and Society Division Turns 22

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Its small size (163 km²), low relief, and location on the easternmost carbonate bank of the Bahama Archipelago, make San Salvador susceptible to tropical cyclones. Both aboriginal and post-Columbian societies have exploited the periphery of this and other Bahamian islands – geographies most vulnerable to the impacts of climate change. Documentation of recent storm effects can provide insights on improving societal resilience.

Hurricane Joaquin (October 2015, a strong Category 3 storm) was the most recent cyclone to pass directly over the island with sustained winds of 190-210 km/hr. About 80% of buildings on the island were damaged, including the airport, which delayed our assessment of storm effects until January 2016. At that time, we documented significant changes to coastal boulder deposits at two sites that had been monitored since 2012: 1) Singer Bar Point (SBP) along the relatively low-energy, gently seaward-sloping ramp on the lagoon- and reef-protected north coast; and 2) rocky cliff bench, 3-5 meters above sea level, at The Gulf (TG) on the high-energy south coast. Storm waves overtopped TG cliffs and modified the sharp-crested, narrow boulder ridge into a broad, vegetation-free field. New boulders up to 3 m in diameter were emplaced on cliffs, and 1-3 ton blocks from prior storms moved up to 26 m inland. Calculated flow velocities needed to initiate their transport were 2.6-5.7 m/s. The boulder-ridge edge moved landward 4-5 m, exposing a Pleistocene/Holocene boundary terra rossa paleosol and marking the extent of storm erosion. 

Sandy coastlines along the east and west sides of the island also experienced significant erosion. On the east coast, the seaward-facing wall of Fortune Hill Cemetery was destroyed and replaced by a ~2 m vertical foredune scarp. Some foredune scarps were showing signs of repair months after the storm, and ten years later, the dune and beach system adjacent to the cemetery has fully recovered from Joaquin erosion. 

Small boulders and finer-grained sediment at SBP are frequently moved by winter storms associated with cold fronts that approach from the north, but TG cliffs remain mainly unaltered ten years after Joaquin, except for the return of vegetation. In conjunction with the striking differences documented at TG immediately before and after Joaquin, this underscores the intensity of this extreme weather event.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-8656

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