Researchers studying volcanoes are looking towards drones for assistance to collect samples of discharged volcanic gases. This would reduce the risk for researchers and help in predicting any disaster that might be awaiting for the people living in proximity

Volcanic eruptions are impossible to anticipate with absolute precision. However, a volcano's hot and pungent emissions can be used to infer information about impending eruptions. The timing, length, or intensity of impending eruptions may be inferred from these gases, which can assist local authorities in determining if and when thecommunities in the proximity need to be evacuated.

On the earth, there are often up to 50 volcanoes that are actively erupting at any given moment. In many of these volcanoes, heated gases like steam and carbon dioxide are more likely to be released than lava. Although it might be risky, collecting these gases is essential to understanding the puzzling behaviour of volcanoes.

Collecting samples of gases being discharged by volcanoes is dangerous but now drones are making it safer and easier than ever before.

Fiona D'Arcy, PhD candidate in Earth Sciences at McGill University has been visiting gassy volcanoes regularly to catch them just before, during or after an eruption.

She has worked with other scientists and engineers to measure volcanic gases with a variety of devices attached to drones.

She said, “Our latest research uses drones to capture volcanic carbon dioxide at Poás volcano in Costa Rica. We measured the isotopes of carbon in this carbon dioxide and discovered a pattern in the way these chemical fingerprints change during different stages of activity."

Where are drones helpful in studying volcanoes?

Carbon dioxide is everywhere: in the air we exhale, in vehicle exhaust and dissolved in magma. At volcanoes, it escapes from magma to the surface through cracks and hydrothermal systems (like the geysers in Yellowstone National Park), by seeping through the soil or by puffing out in a plume of gas.

Researchers can now evaluate the stable carbon isotopic ratio, a distinctive chemical composition that reveals the source and route the CO2 took to the surface, by acquiring a sample of this volcanic carbon.

Each volcano around the world produces a unique range of these carbon isotopes which change when the volcanic system changes.

Earlier, it took a while to get each sample since the researchers had to descend into a crater, placing them in danger for each second they were there. Researchers have begun deploying unmanned aerial systems (UAS), or drones, into hazardous locations as a result of the development of these devices.

How are drones being employed?

To do this, researchers connected gas sensors to the UAS's onboard communications systems using switches and electronic components. With the aid of a pump and sensors that would alert the pilots when they hit the gas plume, the volcanic CO2 would be drawn in through a network of tubes. The pilot may select when and where to take the gas sample with a simple switch on the remote control while remaining at a safe distance.

D'Arcy while telling about her experience in application of drones to study the Poás volcano in Costa Rica said, “We arrived in Costa Rica in April 2019 with our shiny new drone set-up, which we launched at the rim of Poás volcano and which crashed almost immediately. Thankfully, our team whipped up a quick solution for our second drone — a pump and switch hanging from the drone in a laundry bag. It worked flawlessly."

She explained, “To avoid further losses, we got up close to the crater and flew our assembly directly above it. Later that day, we looked at the stable isotopes of carbon in our drone samples and in the samples we took from the ground. After we accounted for the mixing with the regular air in the drone samples, the two results were strikingly similar. Our drone assembly worked!"

A pattern emerges

When D'Arcy started compiling data with all the carbon isotopes measured at Poás volcano in the past, a trend appeared in how the balance of isotopes shifted when the volcano was behaving differently.

During eruptive phases, when Poás was making wet explosions releasing extra hot, sulfur-rich gas, the isotopes of carbon slipped down to lighter values. Meanwhile, during quieter phases when the volcano was sealed, the isotopic balance rose to heavier values.

D'Arcy said that, “With this new insight, we could look back even further and stitch together our data with isotope data from older activity. We saw that this pattern was repeating itself, with the carbon isotopes alternating between heavy an light values over the last 20 years of activity at Poás."

There were relatively heavy values when the volcano was sealed and there were relatively light values when the volcano was open.

Now researchers know exactly what warning signs to look for in future carbon isotope samples taken from the volcano to know if the volcano is about to erupt.

Future research

D'Arcy mentioned, “Thanks to drones, we captured the first CO2 from Poás volcano since 2014. Volcanic gases sampled before our work were all taken by hand by brave volcano scientists climbing down into the crater of Poás."

With the onset of gas-capturing drones, carbon dioxide at volcanoes can start to be sampled more frequently. This will fill the gaps in the timeline and help us understand and forecast eruptions.

(With inputs from PTI)