Seismic Sensors Monitor Sea Ice and Finds Critical Data

These interactions can vary seasonally and cause chaos as larger, dense ice packs cause more forceful impacts, while smaller chunks pose different risks, such as unpredictable drifting and collision patterns.

Previous methods of tracking changes in sea ice have primarily relied on satellite imagery, which offers visual data on ice extent and movement but is unable to reveal what occurs beneath the surface or within dense ice packs. 

Radar can provide more detailed visualizations of ice features. Combining this with seismic data can significantly enhance understanding of ice dynamics.

Seismic signals (measurements of ground vibrations caused by ice interactions) can provide data on the forces and types of impacts occurring beneath or behind visible surfaces, capturing information on how different ice interactions generate vibrations and transmit energy across the landscape.

The Current Study

The research was conducted near Utqiagvik, Alaska, a key location due to its proximity to rapidly changing Arctic sea ice conditions. The team used a range of sensors to collect data during specific ice interactions on January 4 and April 8, 2022. 

These events involved large chunks of sea ice striking stable, land-bound ice, creating naturally occurring occasions to observe ice dynamics under varying seasonal conditions.

The primary data collection tools included broadband seismometers and distributed acoustic sensing (DAS) via fiber-optic cables, laid across the coastal tundra zone. The broadband seismometers measured ground vibrations caused by ice impacts, providing a seismic record of tremors generated during the interactions.

The DAS system, a relatively novel approach in this context, turned a buried fiber-optic cable into a dense seismic array that recorded strain signals along its full length.

Alongside seismic sensors, the researchers used marine imagery in post-event analysis to estimate ice motion through image correlation techniques. This analysis revealed broad-scale movement and timing of key events.

Integrating seismic data with these radar-based observations allowed researchers to cross-evaluate findings and interpret the underlying processes far more effectively than would typically be possible.

To make the seismic activity more intelligible, the data was converted into audio signals: vibrations were sped up approximately 200 times, producing eerie, audible representations of the tremors. This conversion enabled a more intuitive way of understanding the data, through "listening" to the ice.

Results and Discussion

The study revealed several key findings into Arctic ice dynamics.

First, the seismic signals correlated strongly with radar-derived velocity changes, confirming the team's hypothesis that distinct ice interactions produce characteristic tremor patterns. They observed that the impacts of larger, denser ice packs generated sustained harmonic tremors that could be distinguished from the more sporadic vibrations caused by smaller ice fragments.

Researchers categorized the tremors into two types: chaotic and harmonic. Chaotic tremors were broadband and irregular, often associated with sudden brittle ice failure, while harmonic tremors were rhythmic and long-lasting, indicative of repetitive stick-slip motion between ice masses.

The conversion of seismic data into audio revealed the vibrations of ice interactions as rhythmic sounds. Accelerating playback made it easier to discern variations in ice friction, velocity, and impact energy, revealing subtle differences in the nature of ice movements.

The January ice event produced lower-frequency signals, linked to the transfer of considerable momentum during large ice impacts. These large impacts have the potential to cause significant hazards: coastal erosion, destruction of infrastructure, or unpredictable ice movement that can threaten ships and local populations.

The researchers demonstrated that seismic data complements radar imagery by providing information on processes occurring beneath the surface or within dense ice formations. 

While radar-derived images captured surface displacement patterns, seismic tremors successfully uncovered the underlying stress mechanisms and mechanical coupling between ice types. Radiowaves alone can visualize ice movement but cannot capture the forces involved or explain the variability in impact severity. This combined approach enhances the ability to evaluate hazards, especially in remote or harsh regions where visual monitoring is limited.

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Conclusion

The study successfully demonstrated that integrating seismic sensors with radar imaging provided a powerful new approach to understanding Arctic sea ice dynamics and could support future efforts to monitor evolving ice conditions. By identifying characteristic seismic signatures of different ice interactions, researchers can better interpret the forces driving ice movement and impact severity.

Looking ahead, the team intends to expand long-term seismic monitoring and integrate it with radar observations to better characterize seasonal ice behavior. These efforts could help improve situational awareness for communities vulnerable to ice-related hazards.

This research clearly demonstrates that bridging the gap between visual observation and subsurface understanding could provide a comprehensive framework for deciphering the complex processes of Arctic sea ice, and strengthen our capacity to track environmental change in coastal polar regions.

Journal Reference

Rocha dos Santos, G., & Zhu, T. (2025). Seismic tremors from sea-landfast ice interactions near Utqiagvik, Alaska. Geophysical Research Letters, 52,e2025GL117458.