The seafloor plays an important ecological and societal role. However, many fundamental questions remain about the geological processes that shape this environment. Earlier this year, MBARI deployed innovative new technology that could change how scientists monitor the processes that shape the seafloor.

Geo-Sense is a portable distributed acoustic sensing (DAS) system that measures shifts in laser light across fiber-optic cables to detect changes to the seafloor. A team of MBARI engineers, marine operations crew, and scientists deployed the first prototype of the Geo-Sense instrument in January and recently recovered the device to analyze its data. This project is the result of a collaboration between MBARI and Sintela, bringing together expertise in fiber-optic sensing, marine engineering, and seafloor geology. 

“Geo-Sense represents a significant milestone in the adaptation of distributed acoustic sensing technology for ocean science. This groundbreaking instrument was made possible by the innovation of the MBARI team and our collaborators, and paves the way for the wider application of this powerful new sensing technology for seafloor hazard detection, coastal resilience, and deep-sea exploration,” said Senior Scientist Aaron Micallef, who leads MBARI’s Seafloor Processes Team.

DAS is a ground-breaking technology that transforms fiber-optic cables into dense sensor arrays. By measuring the phase changes in laser light along the cable, it can detect disturbances on the seafloor. DAS sends ultrashort pulses of laser light down a fiber-optic cable, analyzing millions of tiny reflections (backscatter) to essentially convert the cable into a motion sensor. DAS can track changes over long distances—more than 100 kilometers (62 miles)—and record seafloor processes in high resolution. With DAS technology, researchers can observe changes to seafloor terrain and geology that are one to 10 meters (three to 33 feet) large. Providing coverage over a larger area and for longer periods of time means this technology will allow researchers to study seafloor processes that previously were too challenging to observe.

DAS technology has recently been shown to be a powerful tool for detecting seafloor hazards, including earthquakes and currents. However, researchers have had to rely on the availability of commercial cables, which are difficult to access for scientific purposes and often are not located in sites of geological interest. Geo-Sense is a new portable DAS system that can be deployed wherever there is a seafloor process of interest. 

On January 28, 2025, the Geo-Sense prototype was successfully deployed from MBARI’s research vessel Rachel Carson on the southern flank of Monterey Canyon. The system includes a one-kilometer (3,281-foot) armored fiber-optic cable, specialized connectors, and a low-power DAS interrogator powered by a 30-kilowatt-hour lithium primary battery pack. Following deployment, the team successfully downloaded the instrument’s data. They will compare that data with measurements collected by seismometers and other instruments deployed in Monterey Canyon by MBARI’s Continental Margin Processes Team. This will help assess how well Geo-Sense can detect and characterize sedimentary flows within the canyon.

The team is preparing for a second deployment of the Geo-Sense instrument in late 2025 at a different location in Monterey Canyon. In 2026, they plan to deploy Geo-Sense to determine how effective DAS is for monitoring active cold seeps.

MBARI scientists will use Geo-Sense to monitor a range of seafloor processes, such as sediment transport, underwater landslides, and fluid seepage. These processes can be relatively small scale, yet they play a major role in shaping continental margins. The instrument will allow researchers to collect long-term, high-resolution data, and bridge major geographic gaps in monitoring the seafloor.

“We aim to transform our understanding of the onset and evolution of active seafloor processes. Data from Geo-Sense will enhance early warning systems for offshore natural hazards and improve insights into the role of seafloor processes in oceanographic dynamics,” said Micallef.

Story by Senior Science Communication and Media Relations Specialist Raúl Nava

For additional information or images relating to this article, please email pressroom@mbari.org.