Salt leaching by freshwater and its impact on seafloor stability: An experimental investigation

Offshore freshened groundwater (OFG) has been documented in many continental margins worldwide. OFG systems are dynamic, expanding and contracting with falling rise sea-levels. long thought to be an important geomorphic agent margins, either via active discharge at the seafloor, which can erode depressions, or generation of excess pore pressure, deform sediments cause slope failure. It also proposed that flow drive loss sediment shear strength salt leaching, when seawater pores is replaced by freshwater. Here, we measure changes geotechnical properties seafloor clayey silt due leaching using flushing experiments, assess implications these on stability siliciclastic 2D limit equilibrium modelling. We document a ∼ 50% decrease undrained cohesive after flushing, as well its strength, bulk density, moisture content, similar reported for subaerial quick clays undergoing leaching. When applied theoretical submarine domain 300 m wide 100 high, estimate trigger failure thickness flushed layer >3.5 gradient >3°. Such conditions primarily satisfied shallow close shoreline. Salt merits consideration potential mechanism destablising sedimentary slopes.