SCIMPI: A versatile seafloor observatory for changing environments

The Simple Cabled Instrument for Measuring Parameters In-situ (SCIMPI) is a new seafloor observatory instrument. SCIMPI is designed to take subsurface time series measurements of temperature, pressure and resistivity in the sub-seafloor. This instrument has a battery operational life of approximately two years, which can be replaced with a battery pack using a remotely-operated vehicle, and provides high resolution measurements of physical properties in the sediment. With either periodic battery replacement or connection to a fiber-optic cable, SCIMPI is a long-term observatory for understanding sub-seafloor dynamics. The main advantage of this system is the reduced equipment and installation requirements making this tool an affordable and versatile system for scientific research. The pressure and temperature sensors, integrated into the system, have been successfully used in other marine industrial and scientific applications. Its electrical resistivity sensor, casing, and array assembly are uniquely designed and can be adapted for each mission. SCIMPI is currently in its last phase of testing prior to deployment in an Integrated Ocean Drilling Program borehole. This first SCIMPI is designed for a water depth of 1000 m and a sediment depth up to ~300 m below seafloor. But future assemblies can be tailored for deeper conditions and environments. Here we present the SCIMPI design, deployment options, and its scientific potential in a long-term ocean observatory. Science applications include studies of fluid flow, hydrate formation, and seismically induced pore pressure changes. The cost of this instrument will enable these measurements to become more commonplace, thereby improving our temporal and spatial knowledge of sub-seafloor gas, fluid and pore pressure activity. Most notable of the target deployments for SCIMPI are sub-seafloor gas hydrate sites and sites with biogenic methane. Understanding the dynamics of methane's role in the oceans as climate change proceeds will contribute to a better understanding of Earth's carbon budget.