SCIMPI installation site

Expedition 341S is the first full-scale test of the SCIMPI prototype. Nine modules were configured and connected to each other via SCIMPI cable for deployment at Site U1416 (proposed Site CAS05-CORK) (Figs. F1, F2, F3, F4; Table T1), a site of known gas hydrate occurrence (Riedel, Collett, Malone, and the Expedition 311 Scientists, 2006; Riedel et al., 2006).

The upper 140 meters below seafloor (mbsf) at Site U1416 consists of slope sediments that overlie accreted terrain sediments. The boundary between the slope and accreted sediments, based on seismic stratigraphy, occurs at ~140 mbsf. The bottom-simulating reflector (BSR), interpreted as the base of the gas hydrate stability field, is located at ~225 mbsf. SCIMPI was configured so that modules measure parameters in the slope and accreted sediment as well as above and below the BSR.

The depth of each module (Figs. F4, F5) was selected based on the known and estimated physical properties and pore water chemistry from previously drilled Site U1328 (Lado Insua et al., 2012). The command module is at the top of SCIMPI and is used in autonomous SCIMPI mode to control data acquisition and store data. In this first deployment of SCIMPI, the estimated lifetime of the batteries is ~2 y. As Site U1416 is also located within 180 m of an Ocean Networks Canada NEPTUNE observatory junction box, the proposed plan is to connect SCIMPI to the observatory before the end of life for the modules’ batteries.