The first International Ocean Discovery Program (IODP) Core-Log-Seismic Integration at Sea (CLSI@Sea) workshop, held in January–February 2018, brought together an international, multidisciplinary team of 14 early-career scientists and a group of scientific mentors specialized in subduction zone processes at the Nankai Trough, one of the Earth's most active plate-subduction zones located off the southwestern coast of Japan. The goal of the workshop was to leverage existing core, log, and seismic data previously acquired during the IODP's Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE), to address the role of the deformation front of the Nankai accretionary prism in tsunamigenic earthquakes and slow slip in the shallow portion of the subduction interface. The CLSI@Sea workshop was organized onboard the D/V Chikyu concurrently with IODP Expedition 380, allowing workshop participants to interact with expedition scientists installing a long-term borehole monitoring system (LTBMS) at a site where the workshop's research was focused. Sedimentary cores from across the deformation front were brought onboard Chikyu, where they were made available for new description, sampling, and analysis. Logging data, drilling parameters, and seismic data were also available for investigation by workshop participants, who were granted access to Chikyu laboratory facilities and software to perform analyses at sea. Multi-thematic presentations facilitated knowledge transfer between the participants across field areas, and highlighted the value of multi-disciplinary collaboration that integrates processes across different spatiotemporal scales. The workshop resulted in the synthesis of existing geophysical, geologic, and geochemical data spanning IODP Sites C0006, C0007, C0011 and C0012 in the NanTroSEIZE area, the identification of key outstanding research questions in the field of shallow subduction zone seismogenesis, and fostered collaborative and individual research plans integrating new data analysis techniques and multidisciplinary approaches.

started from 2007, has explored evolutionary processes of deformation and accretion in shallower portion of the Nankai accretionary prism Strasser 2009) with understanding the tectonic and sedimentary backgrounds Clift et al; 2013; Pickering et 2013). The first workshop entitled Core-Log-Seismic Integration at Sea (CLSI@Sea) held in January-February 2018, together with IODP expedition 380 as a part of NanTroSEIZE. The expedition 380 aimed to install a new Long-Term Borehole Monitoring System (LTBMS) in the toe of the Nankai accretionary prism, while the CLSI@Sea reanalyzed the legacy data from the same site acquired during previous expeditions. Lithology group of CLSI@Sea reviewed the previous lithological descriptions and ages including the sites C0006, C0007, C0011, and C0012, of incoming sediments and toe of prism sites to understand the depositional process of slope sediments and development of decollement and the branching thrusts forming the frontal prism. At Site C0007 of