Integrated Ocean Drilling Program (IODP) Expedition 315 is an integral part of the Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) complex drilling project based on IODP Proposals 603-CDP3, 603A-Full2, 603B-Full2, 603C-Full, and 603D-Full2 (available at This addendum presents the revised operations plan for Expedition 315 based on new site survey data and operational requirements. Several new alternate and contingency sites are described that were not previously identified in the Expedition 315 Scientific Prospectus.