Subglacial volcanoes are the result of volcanic activity that takes place beneath a glacier. As the result of magma and heat, part of the glacial surface melts to form a lake. While many subglacial volcanoes are found in Antarctica, there are some in Iceland and even Canada.
According to a recent article published in The Seismic Record, researchers were especially interested in the volcanic activity at the Vatnajokull glacier in Iceland, where the Grimsvotn volcano remains active. Grisvotn it’s the most active volcano in Iceland and, due to its regular eruptions, has been known to cause significant problems for human transportation, health, and agriculture. Better understanding how to measure it’s activity is important.
The area near Grimsvotn is remote, however, and it was exceptionally difficult to install a traditional seismic sensing system. In response to these challenges, researchers explored the use of fiber optic cables as a way of detecting volcanic tremors associated with subglacial volcanoes.
Specifically, the researcher team used a roughly 12 kilometer fiber optic cable near the volcano to gather information and test the cable's ability to detect volcanic tremors. The cable made use of Distributed Acoustic Sensing (DAS) methods. DAS turned the fiber optic cable into a type of seismic sensor. Laser pulses were shot along the cable and back. A tremor would disrupt this flow, which could give researchers more information about the nature of seismic activity.
Interestingly, researchers found that the ice sheet surrounding the volcano acted as a natural amplifier of the seismic tremors. Without that amplification, researchers believe a traditional approach to detecting seismic activity would have overlooked the volcanic tremors the team picked up with fiber optic cables.
One of the most crucial takeaways from the team’s work is insight into whether fiber optic cables could work as a tool to monitor subglacial volcanic tremors. Not only do volcanic tremors help detect a potential eruption, but there is a connection between volcanic eruptions and larger earthquakes.