At Vulcano Porto, a humming drone hovers above the crater’s edge, pausing before a laser beam as researchers evaluate its ability to measure volcanic gases for eruption prediction. On the Aeolian island of Vulcano, near Sicily, Marius Schaab of the Technical University of Munich (TUM) stands beside a tripod-mounted gas sensor, awaiting the approach of a drone launched by a colleague. In this stark, moon-like terrain where sulfurous steam rises from the ground, the small propeller craft stands out. Although the Grand Crater last erupted in the late 19th century, it remains highly active with degassing, astonishing visitors permitted to walk its rim. The drone aligns with the sensor’s axis; the sensor emits an invisible laser through the gas plume to the drone, which reflects it back. Schaab explains that the sensor “sends a laser beam through some gas and onto a reflector that measures the intensity of the driving light.” The drone can reposition and adjust angles for comprehensive readings. By using a laser, the sensor avoids direct contact with the corrosive plume—both the drone and ground unit stay outside it, eliminating constant recalibration. An algorithm then builds a gas concentration map within 10 to 15 minutes as the drone follows a preset path up to 60 meters away.
Initial Trials
While drones have assisted volcano monitoring for roughly fifteen years, scientists now aim to refine gas measurement tools for greater accuracy and safety. Nearby, another German team from the University of Mainz operates drone-borne sensors to assess airborne chemical concentrations. Tjarda Roberts, a CNRS researcher in Paris collaborating with the Mainz group, notes two key motives: “One reason for measuring gases and particles is to better understand the impact of volcanic eruptions and emissions on the atmosphere.” She adds, “Another is to anticipate eruptions, because gas composition can shift before an event.” Rising lava pressure forces more gas to escape. The TUM team is field-testing its drone system—capable of 3,000-meter altitudes—on a volcano for the first time.
Enhanced Flexibility
Holding a checklist, Johannes Gutenberg University Mainz student Jonas Krajewski confirms that “Tina,” the 2.5-kilogram drone, is ready for safe flight. It ascends toward the venting gases and, over a 40-minute planned route, enters the fumaroles where temperatures reach 100–140°C. Tina carries sensors for gases, particles, and halogens such as chlorine and bromine. Krajewski states, “We have a very constant output of gas… so we can have very reliable sensor data.” Roberts highlights the drone’s flexibility: it can traverse diluted plume sections and swiftly change direction if the plume shifts. Researchers avoid dangerous on-foot entry into emissions zones requiring masks. “Here we don’t have a major risk of an imminent eruption but there are volcanoes where you can’t reach the summit on foot,” she says, yet with a drone “you can take measurements… without putting yourself in danger.” After skimming sulfur-crystal-speckled rocks, Tina returns to view. Soon, the team will target Mount Etna, Sicily’s 3,000-meter active volcano, following a recent eruption.