Volcanic Gas Emissions: New Insights from New Instruments

A team of scientists at the University of Cambridge and Alphasense Ltd in Braintree, England has developed highly portable, low-power, low-cost instruments for volcanic gas detection and measurement. These new

electrochemical sensor based instruments, with demonstrated capacity to characterise in situ volcanic gas plumes, present a technological advance in volcanic gas emissions monitoring.

”Watch out for any eruptions and don’t fall in!” joked my lab-colleagues as I embarked on my first volcano gas-sensing field expedition to Mt. Etna, Italy, in 2006. Upon our arrival on the Italian island of Sicily, Etna’s

Southeast Crater did in fact erupt, spewing a continuous flow of lava down the mountainside, accompanied by occasional and spectacular explosions that ejected gas, ash, and fragments of rock and molten lava into the atmosphere.

To me, as an atmospheric-scientistturned-rookie-volcanologist, the eruption was an added bonus, but for the 25% of Sicily’s population who live on Etna’s slopes, it was a cause for concern. The Italian volcano observatory team1, now in a state of high-alert, embarked on round-the-clock monitoring of the hazard situation using a combination of seismic, thermal and gas sensors.

Our planned field-testing of instruments for volcanic gas detection was thus particularly timely. Volcanoes release a cocktail of toxic gases and aerosol, at concentrations that can exceed several 100s of ppmv (parts per million) close to the vent. This mixture of gases, at very high concentrations, and accompanied by highly acidic volcanic aerosol, presents a challenge for field measurement scientists: how to build an instrument that can accurately measure the complex mixture of acid gases in a volcano plume, that can withstand harsh, acidic environments, and can be deployed in remote and often very difficult to access regions?