A sedimentary-based history of hurricane strikes on the southern Caribbean coast of Nicaragua

摘要

Multi-millennial hurricane landfall records from the western North Atlantic indicate that landfall frequency has varied dramatically over time, punctuated by multi-centennial to millennial scale periods of hyperactivity. We extend the record geographically by presenting a paleostrike record inferred from a four-core transect from a marsh on the Caribbean coast of Nicaragua. Fossil pollen indicates that the site was a highly organic wetland from ~. 5400-4900. cal. yr BP, at which time it became a shallow marine lagoon until ~. 2800. cal. yr BP when it transitioned back into swamp/marsh, freshening over time, with the present fresh-to-brackish Typha marsh developing over the very recent past. Hurricane Joan, 1988, is recorded as a distinctive light-colored sand-silt-clay layer across the top of the transect, identifiable by abrupt shifts in color from the dark marsh deposits, increased grain size, and two upward-fining sequences, which are interpreted as representing the storm's traction and suspension loads. The six layers identified as hurricane-generated display temporal clustering, featuring a marked increase in landfall frequency ~. 800. cal. yr BP. This pattern is anti-phase with the activity pattern previously identified from the northern Caribbean and the Atlantic coast of North America, thereby opposing the view that hyperactivity occurs simultaneously across the entire basin.