Seafloor features identified as headward eroding mass failure scarps were digitized by hand from high-resolution multibeam bathymetry compilations (30 meter grids) across the Cascadia subduction zone, which spans the region offshore of northern California, Oregon and Washington. These features were initially published by Hill and others (2022; https://doi.org/10.1016/j.epsl.2022.117797) and here were present an updated version of this dataset.