Laser-equipped autonomous drones could warn about the next big volcanic eruption
A new autonomous measurement system has been designed to map volcanic gas concentrations with a low measurement error (~5%). Researchers at the Technical University of Munich (TUM) stated that the drone- and laser-based system could prevent natural disasters in the future.
Tracking the ratio of carbon dioxide to sulfur dioxide offers a direct window into subterranean volcanic processes. To measure volcanic gases, an automated ground cart tracks a drone up to 60 meters (196 feet) away, firing a laser beam through a hazardous haze of sulfur and steam.
The testing was conducted on the Aeolian island of Vulcano off the coast of Sicily.
Drone mapping system for volcanic eruptions
Volcanoes release massive amounts of carbon dioxide and sulfur dioxide as rising magma experiences a drop in pressure. The ratio between these two gases changes predictably according to depth, and it acts as a natural countdown clock for eruptions. An eruption is likely imminent when CO2 levels spike sharply and then plunge.
However, getting an accurate measurement of the volcanic gases has been not straight forward. Ground-level testing often gets distorted by background emissions from surrounding soil and vegetation, while flying delicate sensors directly into corrosive plumes rapidly destroys the equipment. Furthermore, using standard drones introduces downwash from the propellers, which stirs up and dilutes the gas plumes required for measurement.
TUM overcame these issues by using light. Marius Schaab and a team at TUM’s MIRMI Robotics Institute deployed a two-part remote system. A ground station shoots an open-path laser through the gas cloud, aiming directly at a reflector mounted on a drone flying safely on the other side.
As CO2 absorbs specific wavelengths of light, the beam loses a tiny fraction of its strength as it cuts through the vapor.
The drone zips along a pre-programmed grid for 15 minutes, capturing up to 3,000 measurements. Back on the ground, a smart algorithm factors in local wind data and translates the fading laser signals into a highly accurate, 3D tomographic map of the gas cloud.
Less chances of error
The island of Vulcano hasn’t actually had a major eruption since the late 19th century (1888–1890). However, it is an ideal testing ground because it remains in an active, intense phase of “degassing.”
Altogether, the system gives a clear picture of volcanic activity with a 5% margin of error.
“Our goal is to automate the measurement and mapping processes and have artificial intelligence interpret the data,” said Prof. Achim Lilienthal, deputy director of the TUM MIRMI Robotics Institute and head of the Chair of Perception for Intelligent Systems at the TUM School of Computation, Information, and Technology.
Safer volcanic forecasting is now possible thanks to this new system design that keeps humans out of harm’s way and electronics away from corrosive plumes.
Every volcano has its own fingerprint. From the volatile peaks of Mount Etna to the restless Phlegraean Fields near Naples, understanding these unique gas signatures is important for assessing volcanic hazard.
Other researchers are tackling the problem from inside the cloud. Over at Johannes Gutenberg University Mainz, Prof. Thorsten Hoffmann’s team is flying drones directly into the thick of volcanic plumes. It uses specialized onboard hardware and photometric cells to track light absorption and electrochemical reactions on electrode surfaces, logging continuous chemical profiles along the flight path.
