Distributed fiber optic sensing is transitioning from an experimental technique to a standard observational tool in seismology and geoscience. What began as the use of telecommunication infrastructure for seismic monitoring is now evolving to a designed sensing system through both instrumental and methodological advancements.

To retrieve information about physical changes along cables, current fiber optic sensing technologies can exploit the interaction between light and matter i.e., using conventional Rayleigh, Brillouin, and Raman scattering. Alternatively, observables can be measured via light interferometry or state of polarization sensing. Interrogators extract information from telecom-grade fibers, exploiting both telecom and non-telecom frequency bands, or from specialty fibers and multi-core designs.

Despite rapid progress, key challenges remain in converting distributed optical measurements into reliable geophysical observables. Translating fiber deformation into true geophysical observables via instrumental response demands improved deployment schemes encompassing cable and fiber embedment geometries, coupling between cable and medium, and quantitative models of cable-to-fiber strain transfer. In parallel, production of massive observable data volumes necessitates new solutions in edge computing, compression schemes, and machine learning to transform how datasets are acquired, reduced, and interpreted.

The session will cover contributions on technological and methodological breakthroughs that push the boundaries of what fiber optic sensors and sensing systems can measure and how they operate. We seek contributions addressing known as well as emerging sensing technology such as designs of next-generation interrogators and specialty fibers, quantifying and improving instrumental response through innovative cable design and ground coupling schemes, as well as extraction of diverse observables (including rotation, stress and strain tensor components). In addition, methodological advances in architectures for edge computing, processing and intelligent data management are welcome.

We invite instrument developers, telecom and optical engineers, as well as method innovators to showcase the developments that will define the next generation of fiber optic sensing tools for the geosciences.

The possibility of turning fiber-optic cables into environmental sensors has paved the way for a new paradigm of observations in geosciences, enabling spatially dense measurements of strain, temperature, and environmental parameters along fibers. The potential to exploit existing fiber-optic infrastructures deployed for telecommunications further increases the applicability of these techniques, enabling environmental monitoring in harsh or remote areas where the deployment of standard instruments is unfeasible. This rapidly evolving technology has already demonstrated significant potential for high-resolution observations in poorly instrumented environments such as volcanic flanks, geothermal fields, ocean bottoms, and glaciers. Moreover, the dense distribution of fiber networks in urban areas opens new opportunities for transforming smart-city applications and infrastructure monitoring.

While the benefits of fiber-optic sensing for conventional monitoring are becoming clear, real-time processing of these data could further enhance their societal impact, with promising implications for the early warning of hazardous phenomena. In volcanic settings, real-time analysis of low-frequency strain can provide valuable information on ongoing eruptive activity, while fiber-optic cables deployed near seismogenic sources could increase lead times for earthquake early-warning systems. At the same time, the growing frequency of extreme meteorological events associated with climate change—such as flash floods or avalanches—calls for monitoring systems capable of rapidly detecting potentially devastating phenomena. Real-time urban monitoring may also contribute to improving the viability and efficiency of smart cities, where fiber-optic sensing could play a key role.

We encourage contributions on operative or potential applications of fiber optic technologies for real-time monitoring in various natural, urban or industrial environments. Contributions highlighting the integration of conventional sensors into fiber-optic networks (e.g. SMART cables), as well as focusing on the challenges of real time processing are welcome. We also strongly encourage contributions that leverage artificial intelligence and machine learning for real-time monitoring, including automated analysis and decision-support systems for early warning applications.

Fibre-optic sensing has rapidly evolved from a niche technology into a versatile observational tool capable of operating in environments that are challenging or inaccessible for conventional instruments. Its high sensitivity to measurements (eg: strain, temperature, pressure) and logistical advantages led to its increasing usage beyond standard terrestrial settings, opening new scientific frontiers.

This session focuses on the opportunities and challenges of applying fibre-optic sensing in extreme and unconventional environments, including the ocean and volcanic settings, deep boreholes, controlled temperature and pressure laboratory experiments, chemically reactive conditions and extraterrestrial or planetary exploration contexts. We invite contributions that explore novel deployments, experimental designs, and methodological advances enabling fibre-optic measurements where traditional sensors are impractical, as well as innovations that push fibre sensing technology into previously unattainable extreme settings.

By bringing together numerical simulations, laboratory and analogue experiments and field deployments, this session aims to highlight recent breakthroughs, discuss remaining challenges, and identify future directions for fibre-optic sensing, from controlled laboratory experiments to the deepest oceans and beyond Earth.

Traditional geophysical networks often struggle with the "spatial gap"—the inability to capture high-resolution data in remote, rugged, or underwater environments. Distributed Acoustic Sensing (DAS), and other fiber-based techniques (e.g. DTS), have fundamentally shifted this paradigm. Fibreoptic sensing not only allows for efficient deployments that sample with unprecedented spatial and temporal density, but also to turn existing telecommunications infrastructure into environmental sensors.

This session invites contributions that explore the application of any fiberoptic sensing methods to monitor any natural processes. In particular, this session aims to highlight how increased spatial and temporal sampling can revolutionise our understanding of Earth’s dynamic systems, from the cryosphere to the deep ocean.

Potential topics include (but are not limited to):

· Cryospheric Monitoring: Studying glacial movement, calving events, and permafrost degradation.
· Hydrological Processes: Monitoring groundwater fluctuations, river discharge, and bedload transport.
· Volcanic systems: Imaging and monitoring magma transport and storage, and volcanic hazards in general.
· Oceanic and Coastal Sensing: Utilizing subsea cables for ocean bottom seismology, internal wave detection, and storm surge monitoring.
· Geohazard Observation: Early warning and characterization of landslides, debris flows, avalanches, and other alpine mass movement activity.
· Ambient Noise based studies and novel Signal Processing techniques: Innovative methods for extracting environmental signals from complex, noisy datasets.

We hope that the session will support a cross-disciplinary dialogue, exploring how fiberoptics can move beyond traditional seismology to become a tool for contributing to environmental studies and monitoring strategies more broadly. We encourage submissions detailing field experiments, theoretical modelling, and the integration of fibreoptic sensing with traditional or other sensor networks.

This session focuses on the use of fibre-optic sensing to observe, understand, and manage complex urban systems. Beyond the sensing technologies themselves, it highlights how fibre-optic measurements are integrated into the built environment to support resilient, safe, sustainable, and smart cities.

Topics include, but are not limited to: urban subsurface characterization and ground stability monitoring; earthquake detection, early warning, and urban hazard assessment; structural health monitoring of critical infrastructure such as bridges, tunnels, and buildings; transportation and mobility sensing across rail and road networks; environmental monitoring in urban settings; monitoring of utilities and energy systems, including pipelines and power cables; smart-city sensing using telecommunication fibre networks; multi-physics fibre-optic monitoring; and large-scale data processing, cloud and edge computing, and machine learning for real-time applications.

By bringing together researchers, engineers, and practitioners across geoscience, civil engineering, data science, and urban planning, the session aims to advance the transformative role of fibre-optic sensing for resilient and smart cities.