Exploring the emerging field of fibreoptic environmental monitoring

For decades, fibre optic cables have formed the invisible backbone of global communications.  

Today, those same strands of glass are quietly emerging as powerful tools in environmental monitoring, offering real-time data collection across vast distances with extraordinary spatial resolution and often without deploying a single new sensor.

This evolution hinges on a suite of distributed sensing technologies that repurpose telecommunications infrastructure into environmental observatories.  

With many monitoring professionals already working in remote, hazardous, or otherwise hard-to-instrument environments, the ability to turn existing cable networks into sensor arrays is proving transformative.

A new era for distributed acoustic sensing

At the heart of this shift is distributed acoustic sensing (DAS), which treats standard fibre optic cables as arrays of virtual microphones.  

By detecting subtle vibrations caused by acoustic signals, seismic waves, or mechanical stress, DAS systems can monitor seismic events, measure traffic flow, or even detect the movement of marine mammals.

Several pilot programs have used DAS to turn subsea internet cables into earthquake sensors, which promises a dramatic expansion of seismic monitoring networks without the cost and logistics of deploying ocean-bottom seismometers.  

In mountainous regions, DAS-enabled fibre is now being used to detect snow avalanches in real time, a critical development for early warning systems.

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Tracking heat flow  

Another technology gaining traction is Distributed Temperature Sensing (DTS), which uses backscattered light within optical fibres to build a detailed thermal map of the surrounding environment.  

With a single cable, DTS can measure temperature fluctuations across tens of kilometres at meter-scale resolution.

This capability is being applied to monitor groundwater temperature profiles, track thermal pollution in rivers, and detect leaks in buried pipelines and industrial facilities.

DTS also plays a growing role in fire detection in tunnels and storage areas, where conventional sensors may be impractical or hazardous to maintain.

Introducing Jonathan Ajo-Franklin

One of the leading figures shaping this frontier is Jonathan Ajo-Franklin, a Trustee Professor of Earth, Environmental and Planetary Sciences at Rice University, who was recently awarded the 2025 Reginald Fessenden Award by the Society of Exploration Geophysicists.  

The award honours a major scientific contribution to exploration geophysics, and in Ajo-Franklin’s case, it recognises his pioneering work in DAS.

Ajo-Franklin’s research demonstrated that unused fibreoptic strands, so-called ‘dark fibre’, can be repurposed for high-resolution seismic monitoring.  

His team’s early studies opened up DAS applications for earthquake detection, groundwater contamination tracking, permafrost monitoring, and even real-time subsurface imaging for carbon sequestration and geothermal energy.

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By showing that existing telecom infrastructure can double as dense seismic sensor networks, Ajo-Franklin helped propel DAS from a niche innovation into a cornerstone of environmental sensing.  

His work has advanced monitoring methods that are safer, less invasive, and more scalable, especially in regions vulnerable to natural hazards and water stress.

“Geophysics isn’t just about exploring the Earth anymore — it’s about protecting it,” Ajo-Franklin said.  

“Whether we’re talking about tracking carbon deep underground or preventing groundwater contamination, the ability to observe the subsurface in real time is essential.”

What are SMART cables?

A new frontier is opening under the ocean: SMART (Science Monitoring and Reliable Telecommunications) cables.  

These next-generation submarine cables integrate environmental sensors directly into fibreoptic infrastructure.  

Once deployed, they can provide continuous, real-time data on seismic activity, ocean temperature, and pressure changes, which are key parameters for tsunami detection and climate modelling.

Projects under development aim to retrofit existing subsea cables or ensure that new installations include environmental sensing capabilities.  

For environmental monitoring professionals, this represents an unprecedented opportunity to gain long-term, wide-area data in some of the most under-monitored parts of the planet.

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What’s so useful about fibreoptic sensing?  

For users of environmental monitoring instruments, fibreoptic sensing offers several compelling advantages:

• Spatial reach: One cable can monitor hundreds of kilometres, reducing the need for multiple discrete sensors.
• Low maintenance: Once installed, fibre cables require minimal maintenance and are immune to electromagnetic interference.
• Non-invasive deployment: Many systems can piggyback on existing infrastructure, avoiding the cost and disruption of deploying new hardware.
• Multi-parameter sensing: Systems can monitor temperature, strain, vibration, and chemical signatures simultaneously.

These capabilities are particularly relevant in sectors like water resource management, energy infrastructure, biodiversity monitoring, and climate science.  

With urban and industrial areas increasingly relying on real-time environmental data, the ability to scale monitoring networks without scaling costs or complexity is a critical asset.

By Jed Thomas