Scientists use drones to learn more about active volcanoes

Volcanic eruptions cannot be predicted with 100% certainty. However, details about an impending eruption can be guessed at by the hot and fetid gases a volcano produces.

These gases provide clues to the timing, duration, or severity of upcoming eruptions that can help local authorities decide if and when to evacuate surrounding communities.

On average, up to 50 volcanoes are actively erupting on the planet at any one time. Many of these volcanoes spew hot gases — like steam and carbon dioxide — rather than lava. Collecting these gases is key to understanding the mysterious paths of volcanoes, but it can be dangerous.

Drones now make it safer and easier than ever.

gaseous volcanoes

For most of the past decade, I have regularly visited such gas volcanoes to capture them just before, during, or after an eruption.

I’ve worked with other scientists and engineers to measure volcanic gases using a variety of drone-attached devices.

Our latest research uses drones to capture volcanic carbon dioxide at Poás Volcano in Costa Rica. We measured the carbon isotopes in this carbon dioxide and discovered a pattern in the way these chemical fingerprints change during different states of activity.

Unique carbon makeup

Carbon dioxide is everywhere: in the air we breathe, in vehicle exhaust – and dissolved in magma. In volcanoes, it escapes from the magma to the surface through fissures and hydrothermal systems (such as the geysers in Yellowstone National Park), seeping through the ground or escaping in a gas cloud.

By taking a sample of this volcanic carbon, we can measure the stable carbon isotope ratio, a unique chemical composition that reflects the source and route the CO2 took to the surface.

Every volcano around the world produces a unique spectrum of these carbon isotopes, which change as the volcanic system changes.

However, it took a long time to collect each sample as researchers had to descend into a crater, putting them at risk for every second they stayed in the danger zone. With the development of Unmanned Aerial Systems (UAS, also known as drones), researchers have started sending these machines into the danger zones.

use of drones

To do this, we used switches and electronics to connect gas sensors to the UAS’ onboard communication systems. The volcanic CO2 was drawn in through a series of tubes using a pump and sensors, which sent a signal back to the pilot when we entered the gas plume. With a push of a button on the remote control, the pilot could choose when and where to take the gas sample from a safe distance.

We arrived in Costa Rica in April 2019 with our brand new drone setup, which we launched from the rim of Poás Volcano and it crashed almost immediately. Luckily, our team came up with a quick fix for our second drone – a pump and switch hanging from the drone in a laundry bag. It worked perfectly.

To avoid further casualties, we got close to the crater and flew our array directly over it. Later that day, we examined the stable isotopes of carbon in our drone samples and in the samples we collected from the ground. After we accounted for mixing with normal air in the drone samples, the two results were strikingly similar. Our drone assembly worked! A Pattern Is Emerging As we began compiling our data with all of the carbon isotopes measured at Poás Volcano in the past, we noticed a trend in how the balance of the isotopes shifted when the volcano behaved differently.

Carbon isotopes slipped to lighter levels during eruption phases, when Poás performed wet blasts releasing particularly hot, sulfur-rich gas. Meanwhile, during quieter periods when the volcano was sealed, the isotope balance rose to heavier levels.

With this new insight, we could look even further back and merge our data with isotopic data from older activity. We saw this pattern repeat itself, with carbon isotopes alternating between heavy and light values ​​over the last 20 years of activity at Poás. There were relatively high readings when the volcano was sealed and relatively light readings when the volcano was open.

We now have a blueprint for what warning signs to look for in future carbon isotopes collected at this volcano as it prepares to erupt.

future research

Thanks to drones, we have captured the first CO2 from Poás Volcano since 2014. Volcanic gases sampled prior to our work were all hand sampled by brave volcanic scientists who descended into the Poás crater. These expeditions were few and far between.

We hope that with the advent of gas capture drones, carbon dioxide sampling at volcanoes will be more common. This will fill in the gaps in the timeline and help us understand and predict eruptions.

(The conversation)