Unit Affiliation: Marine and Polar Geophysics, Lamont-Doherty Earth Observatory (LDEO)
Two earthquakes, M7.0 and M7.2, ruptured sections of the transform fault along Haiti’s southern peninsula in 2010 and 2021. During this project a marine survey in Jamaican waters offshore the recent earthquakes will be conducted to investigate the tectonic and sedimentary effects of these and previous earthquakes in the same region. Sediment cores and high-resolution sub-bottom mapping will image active faults and sample earthquake-triggered sediment deposits. The overarching goal of the project is to compare the new images and samples with pre-existing data collected by the French in 2012 and by collaborators from Jamaica. Results of the project will help improve understanding of fault movement and the character of earthquake-generated sediment deposits and provide insight into the complexities of this plate boundary and the associated hazards. Some key evidence, such as sediment suspended in abyssal water and isotopes that date the remobilized sediments, are short-lived. Other records can be obliterated by erosion. Because of this, the project is time sensitive. Graduate and undergraduate students will be trained during the project.
Continental transform boundaries cross heavily populated regions, and as in the M7.0 2010 and M7.2 2021 Haiti earthquakes, ruptures along these boundaries can cause catastrophic damage and loss of life. Transform boundaries can accommodate only modest changes in relative motion, even slightly oblique motion can make them transpressional or transtensional. These boundaries can evolve into complex, often poorly constrained, systems of faults. The Enriquillo-Plantain Garden Fault (EPGF) is the main strand of a sinistral E-W transform along the southern boundary of the Gonave microplate. The eastern EPGF traces a prominent ridge that forms the 250 km long southern peninsula of Haiti and is rooted on a belt of thrust faulting. The 2010 M7.0 & 2021 M7.2 sequences ruptured the eastern and western segments of this ridge, respectively. Both sequences feature mainshocks that were nearly transcurrent, and thrust after-shocks primarily to the north and west. Such coupling between distinct faults repeated in two earthquake sequences along the same boundary strongly suggests that these faults form a single strain-partitioned, transpressional fault system. The results of the study will constrain whether this system extends to the Jamaica Passage, whether it generates similar large earthquakes in the submarine part of the boundary now loaded by recent earthquakes in Haiti, and the fidelity of the sedimentary record for EPGF earthquakes.
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