The Cascadia Subduction Zone is one of the three Primary Sites for the Subduction Cycles and Deformation (SCD) Initiative (along with Alaska/Aleutians and New Zealand). Cascadia offers outstanding short- and intermediate-term opportunities, in particular leveraging existing and growing onshore and offshore infrastructure associated with EarthScope’s Plate Boundary Observatory (PBO), and deployment of the EarthScope-MARGINS (now GeoPRISMS) Amphibious Array, all part of the ARRA-funded Cascadia Initiative. Work in this region will also build upon a broad spectrum of geological and geophyscial data collected over the past decades and can engage a range of US, Canadian, and international scientists.