Assessing Quaternary Geohazards in Hispaniola and Jamaica Using Seismic, Remote Sensing and Sediment Core Data

The Enriquillo-Plantain Garden Fault Zone (EPGFZ) is a system of predominantly left-lateral strike-slip faults extending through Eastern Jamaica and Western Hispaniola. The fault zone has generated at least one large (\u3e Mw 6) earthquake per century within the last five centuries. These earthquakes include the 2010 Mw 7 Haitian earthquake which killed 300, 000 people and the 1907 Jamaican earthquake which killed ~900 people. Both earthquakes resulted in significant infrastructural damages, tsunamis, landslides and ground fissures. This dissertation provides insights into the history, and societal impacts of active faulting and earthquake triggered geohazards within the EPGFZ. Herein, I show that Eastern Jamaica hosts a previously unrecognized strike-slip fault system that is within 5 km of Kingston, the capital city where two-thirds of the population lives. This newly identified fault system is an extension of a prominent strike-slip fault within the EPGFZ. This study-identified fault system is active and could generate a magnitude 5.8-6.9 earthquake in Jamaica. Historical reports suggest that Mw 5 or greater earthquake within the Jamaican section of the EPGFZ will likely cause slope failures within Kingston, especially Port Royal beach. My analysis of the sands within the upper 2 m of this beach indicates that these sediments strengthen with time since deposition. Possible causes for this sediment strengthening include microstructural changes to the sands (e.g., grain rotation and slippage) with time, relatively small changes to sediment physical properties or both. My studies of the EPGFZ in Hispaniola reveals a complicated relationship between the flooding of Lake Enriquillo and Azuei, earthquake shaking, and climate change. Specifically, I show that the lakes flooded due to changing weather and increased basinal hydraulic connectivity. I further propose that ground shaking and an increase in hurricane frequency were the leading causes for the observed changes in basinal hydraulic connectivity. Together, the studies demonstrate that there is a complicated relationship between tectonics, sediment strength and changes to hydraulic connectivity within the EPGFZ. The studies provide new knowledge of active fault systems that could generate large magnitude earthquakes. They provide insights into the evolution of sediment resistance to liquefaction in Jamaican and possibly across the world. They reminded the scientific community that residents of the Caribbean have to prepare for both earthquakes and hurricanes simultaneously and that these systems can sometimes interact in surprising ways. Along the way, the studies within this dissertation have also helped build a community of American and Jamaican scientists dedicated to improving the lives of Jamaicans and Hispaniolans through geoscience research