The two Toms continue to work together and are both members of Sheffield-based VolcanoTech. They aim to get more instruments onto volcanoes and acquire unprecedented long-term datasets that contribute to volcano research and monitoring. Designing and constructing low-cost scientific instrumentation is crucial for developing countries, where funding for equipment can be quite limited but where many of the world’s active volcanoes are located.

Tell-tale signs

A volcano’s degassing behaviour changes before an eruption, often increasing or decreasing. Since sulphur dioxide is the gas most prevalent at active volcano sites, Tom focused on monitoring this using a UV camera. There were already scientific-grade UV cameras in the field in some locations, but they cost tens of thousands of pounds, whereas Tom aimed to develop a UV camera “an order of magnitude cheaper” and much smaller, making it suitable for permanent installation and remote reporting. Monitoring volcanoes often involves tracking how sulphur dioxide diverges from a baseline and then investigating those changes. Tom’s system uses the Beer-Lambert law of absorption, comparing the optical depth of plume pixels in an image to the background sky radiance.

Tom and his colleagues didn’t know much about Raspberry Pi at the outset, “which made the detailed knowledge and wealth of experimentation by others invaluable when it came to asking specific questions or pulling ideas from pre-existing threads.” A particularly fruitful discovery was a YouTube video by Les Wright which simplified the process of removing the Bayer filter from the camera lens to enhance its sensitivity to ultraviolet light. This worked well for a Raspberry Pi Camera 1.3, but Tom reports that he was unable to remove the Bayer filter in the same way for the newer Raspberry Pi Camera Module. The process in any case requires a fume cupboard and dangerous chemicals (see ‘Warning’ box). Tom originally made use of the UV camera in a spectrometer he used for sulphur dioxide monitoring. Although this worked well, he subsequently decided to focus on the camera-based system.

How predictable

Having created an affordable alternative to the £10,000 scientific cameras, Tom has been working on modifying the camera design so they can be deployed permanently on volcanoes, without the need for human interaction. To date, only Stromboli in the Aeolian Islands, and Etna just to the south, have fixed monitoring. “We are now beginning to build high time-resolution sulphur dioxide emission rate datasets from several volcanoes, the likes of which are quite rare in volcanology,” he says.

Getting the cameras installed on hazardous volcanoes is no mean feat! Using a Starlink satellite connection has helped them overcome the major issue of handling and processing the terabytes of data each camera acquires each year, as well as partially solving issues relating to debugging camera installations remotely. With cameras in the Amazon rainforest as well as the Atacama desert, temperature extremes and huge amounts of rainfall add to the challenges. However, once in place, they’ll give volcanologists significantly improved monitoring capabilities that contribute to longer-term volcanological research – an increasingly critical aspect of their work “since a volcano can exhibit significant changes in activity over a wide range of time scales.