Submarine Paleoseismology Along Populated Transform Boundaries: The Enriquillo-Plantain-Garden Fault, Canal du Sud, Haiti, and the North Anatolian Fault, Marmara Sea, Turkey

Continental transform boundaries cross heavily populated regions and are associated with destructive earthquakes worldwide. The devastating 1999 Turkey earthquakes and the offshore 2010 Haiti earthquake emphasized the urgent need to study the submerged segments of continental transforms. In response, the rapidly evolving field of submarine paleoseismology is focusing its attention on understanding the relationships between sedimentation, seafloor ruptures, and earthquake recurrence intervals along submarine faults. In Canal du Sud, Haiti, the 2010 earthquake-triggered sedimentation events were documented from nearshore to the deep basin by measuring the excess Th-234 in sediment cores. This radioisotope, with a half-life of 24 days, tracked mass wasting, turbidites, turbidite-homogenite units, and a sediment plume that remained in the water column for at least two months after the earthquake. However, the turbidite units in Canal du Sud, Haiti, provide an incomplete record of the region's earthquake history, likely because sedimentation rates are too low for sedimentation events to be triggered by all earthquakes. In contrast, in the Marmara Sea basins, there is very good correlation between turbidites and the historical record of earthquakes dating back 2,000 years. The difference between these correlations is likely related to both sedimentation rates and particulars of the ruptures. Future research along the Enriquillo-Plantain-Garden fault in Haiti and along similar low sedimentation plate boundaries should focus on multiple fault segments in order to obtain complete earthquake recurrence histories.