Over the previous few weeks, we have actually surveyed the Enriquillo-Plantain Garden fault along the Jamaica Passage from west (near Jamaica) to east (near Haiti). The trace of the fault along the seafloor is manifested by direct ridges as high as 1,000 meters. South of the fault there are 3 large basins: the Moran Basin (60 km long), the Navassa Basin (30 km) and Motely Basin (20 km). The basins are bounded by the fault to the north and by a series of ridges to the south. Huge undersea landslides extend from the southern ridges into the basins. The deposits are 10s of kilometers in length and include stones the size of trucks. This recommends that the southern border of this fault zone is tectonically active and earthquakes might be a system that initiate downslope failures and the big slumps.Image of the Enriquillo fault revealing its direct trace, high ridges, submarine sediment failures and basins. The image was prepared from multibeam bathymetry. Brown colors are shallow areas (1,000 meters below water level or less). Dark greens are deep areas, as deep as 3,000 meters listed below sea level. The image is thanks to Sylvie Leroy and the data was collected throughout HAITI SIS oceanographic cruise in 2012. So far we have actually recovered 31 gravity cores. In the cores we discovered a turbidite– sediment deposited by a current of quickly moving, unstable water moving down a slope– that consists of iron-rich minerals and organic material, potentially wood or algae. This is unusual because many sediments that we obtained are “calcareous oozes” composed of small shelled creatures. The turbidites iron-rich minerals are originated from the fault ridges. We will discover more when we open the cores at the Lamont-Doherty Core Repository, however we expect finding more turbidites that will shed light into the earthquake history of the region and aid to better evaluate the danger for Jamaica and Haiti.We put together the day and night shifts for a picture. Front, left to right: Cecilia McHugh, Vashan Wright, Victor Cabiativa, Jhardel Dasent, Richard Kilburn. Back, left to right: Leonardo Seeber, Matthew Hornbach, Chris Fanshier, Benjamin Freiberg, Brian Agee.
South of the fault there are 3 big basins: the Moran Basin (60 km long), the Navassa Basin (30 km) and Motely Basin (20 km). The basins are bounded by the fault to the north and by a series of ridges to the south. This suggests that the southern border of this fault zone is tectonically active and earthquakes might be a system that start downslope failures and the huge slumps.Image of the Enriquillo fault revealing its direct trace, high ridges, submarine sediment failures and basins.
