On a small volcanic island about 25 kilometers north of the Italian island of Sicily, a drone equipped with laser beams flies over the edge of a volcano crater, as part of a scientific experiment led by German researchers to test an innovative system for measuring volcanic gases, which may open new horizons for improving the prediction of volcanic eruptions.

Next to a sensor fixed on the ground, researcher Marius Schapp from the Technical University of Munich waits for the drone, launched by his colleague moments earlier, to approach, ready to start the measurement process. In an area whose geography resembles the lunar environment and appears isolated from the rest of the world, columns of white, pungent sulfur-smelling vapors sweep the air, among which the small propeller-driven drone, encircled by a striking red ring, stands out.

The last eruption of the Vulcano volcano, which rises about 400 meters above sea level, dates back to the end of the 19th century, but the volcano, which can be hiked around its crater, still shows intense gas emission activity. The small drone quickly positions itself on the axis of the sensor on the ground, which then sends an invisible laser beam through the volcanic gas emissions, and its beam reflects off the drone.

Marius Schapp explains the new technology: 'In this way, we obtain the gas concentration based on the speed of light and the position of the reflector' mounted on the drone, explaining that it is enough for the drone to move in the air for the angles to change, thus changing the measurements, noting that 'the problem was previously that we had to move the sensor into the gas cloud,' which required constant recalibration of the device.

Furthermore, by staying away from the gas vents, which pose a risk if exposed for a long time, researchers can do without gas masks. The researcher adds, 'From now on, this drone can stay away (from the gases), as well as the sensor, while the gas column is simply somewhere between them.'

Based on the signals sent by the sensor, algorithms produce a map of gas concentration over a period of 10 to 15 minutes, the time it takes for the drone to traverse a predetermined path at a distance of up to 60 meters from the laser.

This is the first time that a team from the University of Munich has tested on a volcano the technical system that can perform up to 3,000 measurements. After the Aeolian Islands, the team will head to Mount Etna in Sicily.

Drone (iStock)

High flexibility

A little farther away around the volcano crater, another team of German scientists from the University of Mainz uses sensors mounted on a drone to measure concentrations of chemicals in the air. Tjarda Roberts, 46, a researcher at the French National Centre for Scientific Research in Paris who collaborates with the Mainz team, tells AFP that 'one of the reasons for measuring gases and particles is to better understand the effects of volcanic eruptions on the atmosphere.'

She adds that this also improves 'prediction of volcanic eruptions, because the composition of gases can change before an eruption,' especially levels of carbon dioxide and sulfur dioxide. The more pressure exerted by magma rising from the Earth's interior toward the surface, the greater the amount of gases emitted. Therefore, knowing this amount more accurately can help better predict volcanic eruptions.

Carrying a checklist, Jonas Kraijewski, a master's student at Johannes Gutenberg University Mainz, checks that 'Tina,' the name given to the drone, can fly safely. The drone, weighing two and a half kilograms, quickly rises into the air and heads toward the volcano's emissions.

This time, the drone, equipped with a series of sensors that measure gases, particles, and halogens (chlorine, bromine, etc.), penetrates the heart of the fumaroles, which range in temperature between 100 and 140 degrees Celsius.

Jonas Kraijewski, 28, explains that 'what is great here, on this volcano, is that we have a very steady gas flow... which allows us to obtain highly reliable data from the sensors.'

Drones have become a common tool in volcano monitoring for about fifteen years, but scientists are seeking to develop gas measurement tools that are more accurate and risk-free. For Tjarda Roberts, one of the main advantages of the drone is its high flexibility.

She explains, 'We can measure wherever we want, we can measure in volcanic clouds, farther into the atmosphere,' adding that 'sometimes, on the ground, we try to make a measurement, but the cloud drifts in another direction.' Flying along the rocks covered with yellow sulfur crystals deposited by the gas vents, 'Tina' soon reappears on the horizon.

In the coming days, a new challenge awaits the drone: Mount Etna, which exceeds 3,000 meters in height, and has just experienced a new eruption.

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