Collaborative Research: Salt Marsh Geomorphic Response to Rapid Sea-level Rise Using Past Earthquakes on the Oregon Coast as a Natural Laboratory

Salt marshes are societally and economically valuable ecosystems that protect against flooding, improve water quality, and provide wildlife habitat. Additionally, marshes are excellent recorders of environmental history including past shorelines, but it is unclear whether there is a lag between environmental change and what the marsh records. To address this gap, this project will measure lag times between sea-level rise as a result of the 1700 Cascadia earthquake and salt marsh response preserved in sediment records from the Oregon coast. The project will train the next generation of geoscientists and, using the findings, will co-develop actionable strategies with coastal land managers. The project will use stratigraphic analysis and age-dating of sediment cores collected from the Cascadia margin integrated with numerical models of salt marsh geomorphology to answer: (1) what is the time required for marshes to reestablish dynamic equilibrium with relative sea level following an abrupt change in sea level due to the 1700 CE coseismic subsidence?, and (2) following rapid sea-level change, do transitions between intertidal zones occur slowly and linearly, or rapidly and nonlinearly? While focused on Cascadia marshes, these results will be made broadly applicable to marshes globally and have implications for paleo-sea-level and paleoseismic reconstructions. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.