Measuring the fiery pulse beneath Europe’s largest glacier

Iceland’s most active volcano, Grímsvötn, lies beneath the Vatnajökull icecap, Europe’s largest glacier. Its extreme and remote environment limits the data that can be collected. However, with Distributed Acoustic Sensing (DAS), an emerging technology in the field of geophysics, we can study the volcano in unprecedented detail.

We are Sara and Sölvi, doctoral candidates who use seismology to gain insight into the hidden subsurface structures of Earth. Sara is researching the potential of DAS for monitoring volcano hazards, and Sölvi is using large-scale inversions to obtain a global model of our planet.

We had an idea that could revolutionise our understanding of the volcano.

But first, we had to get there.

It takes a full day to travel to Grímsvötn. The experiment was a massive undertaking that required a team of people, three different fibre-optic cables and a snow groomer. We start with a few hours’ drive, until the standard jeeps can take us no farther. We continue with snow scooters, super-jeeps and a snow groomer to carry up all the equipment. Our accommodation: huts specifically designed for scientific research, on top of the caldera rim on the glacier.

Feeling cold already? Actually, as the huts are located atop a volcano, they are uniquely positioned to harness geothermal power… Geothermally heated, they have a constant supply of hot water and even boast a steam room! Given the remoteness, the infrastructure to conduct research is beyond belief.

At Grímsvötn, we installed a 12 km long fibre-optic cable that emits regular laser pulses to record ground deformation every few meters. To ensure a high-quality signal, the fibre-optic cable needs to be buried underground. Burying 12 km of cable into a glacier sounds like a multi-week job. However, one of the local team members designed a custom sled-plough, which allowed us to deploy all 12 km in just two days. The plough was pulled by the snow groomer, automatically burying the cable 50 cm below the snow’s surface.

Before this experiment, the volcano accommodated a single seismic station. Now, we effectively have more than a thousand measurement locations. This increase in data allows us to record smaller events, and to locate their origins.

As this new technique will give data with incredible spatial and temporal resolutions, we hope the experiment will further the field of volcano monitoring. However, this experiment started with plain curiosity. Would it work? What would we measure? Are there any active volcanic signals? Our curiosity has given us many answers already: we can detect a lot of local volcanic and glacial events that conventional instruments could not.

In spite of some initial laser-related hiccups, the whole field campaign was a remarkable success. Flexible planning and innovation by our collaborators were key, and we hope to work more with them in future. Visiting such a remote, beautiful and extreme location as Grímsvötn is an absolute privilege.