One Year of Data of Scimpi Borehole Measurements
Abstract:The Simple Cabled Instrument for Measuring Parameters In-Situ (SCIMPI) is a new subseafloor observatory designed to study dynamic processes in the subseabed using a simple and low-cost approach compared to a Circulation Obviation Retrofit Kit (CORK). SCIMPI was successfully installed at the Integrated Ocean Drilling Program (IODP) Site U1416 during IODP Expedition 341S in May 2013. SCIMPI is designed to measure pore pressure, temperature and electrical resistivity over time in a borehole.
The first SCIMPI prototype comprises nine modules joined in a single array by flexible cables. Multiple floats keep the system taut against a sinker bar weight located on SCIMPI and resting on the bottom of the borehole. All the modules record temperature and electrical resistivity, and three are also equipped with pressure sensors. Currently, SCIMPI operates as an autonomous instrument with a data logger that is recovered using an ROV. The second recovery of the SCIMPI data logger took place during the Ocean Networks Canada maintenance cruise, Wiring the Abyss 2014, on May 25th, 2014.
The pressure sensor data show a stable trend in which tidal effects are observed in through the one year deployment. The temperature measurements in all the modules became stable over time with smaller variations over the last several months. The only temperature sensor differing from this trend is the shallowest, located at 8 meters below seafloor. This module shows a sudden spike of ~20°C that on April 5th, 2014, an event that was repeated several times from April 25th until recovery of modules. The electrical resistivity sensors show variations over time that could be related to gas hydrate dynamics at the Site. Interpretation of these data is speculative at this time but borehole-sealing processes as well as the formation of gas hydrate are potential processes influencing the recordings.
SCIMPI will soon be connected to Ocean Networks Canada's NEPTUNE observatory at Clayoquot Slope node to provide real-time data from this subseafloor observatory.