The four-propeller drone sitting briefly on a rocky and dusty surface in Central America in early March had an impressive diameter of nearly 7 ½ feet.

From afar, however, it appeared as just another small rock or outcrop in the steaming crater of Costa Rica’s Poás volcano.

This small speck had a big and innovative mission: sample gas escaping from the soil of an active volcanic crater about a half a mile wide and about 1,000 feet deep, one of Earth’s largest.

“Our goal was to test a new and safer way of measuring soil degassing at a variety of spots in an active volcanic crater, and we accomplished that goal,” said research assistant professor Társilo Girona of the University of Alaska Fairbanks Geophysical Institute. “The UAF drone team was fantastic, and the equipment performed exceptionally well.”

“It’s a major challenge to work in a setting such as an active volcano crater,” he said. “We learned a lot on this mission, and we’ll be working to make improvements to make this process even better.”

Girona said using unmanned aircraft to efficiently and safely measure soil gas emissions in potentially risky areas has great potential for the field of volcanology.

The 4,800-mile trip from Fairbanks to Costa Rica was a success for both science and technology.

The mission of the four-person UAF team was part of an international gathering to better understand Poás volcano’s plumbing system. Researchers from the United States and elsewhere arrived with different instruments and methods.

It was the second year of the larger Poás community experiment, arranged as part of last year’s Cities on Volcanoes 12th Congress, held in Guatemala. This community experiment is sponsored by the AVERT project, Anticipating Volcanic Eruptions in Real-Time, in collaboration with Oviscori, the Volcanological and Seismological Observatory of Costa Rica.

Poás, one of Costa Rica’s most active and accessible volcanoes, stands 8,848 feet above sea level. The volcano’s crater can be seen in an Oviscori webcam.

In addition to Girona, the UAF team included drone pilots Jason Williams, Matthew Westhoff and James Copple, all of the Geophysical Institute’s drone program — the Alaska Center for Unmanned Aircraft Systems Integration.

The NASA-funded mission was science-based but also tested a new method to enable safer and faster measurements of volcano soil gas emissions, which are especially crucial for advancing knowledge of highly active volcanoes such as Poás.

Girona coordinated a nine-person international team that primarily collected and analyzed carbon dioxide and water vapor and gathered soil temperature and moisture data. Carbon dioxide and water vapor signal magma and hydrothermal fluid movement, while temperature and soil moisture reflect heat and hydrothermal activity.

“One of the big challenges in volcanology is that it has been largely impossible to get close to the action, because it’s dangerous,” Girona said before the trip. “If we are successful with the drones, then we will be showing for the first time that we can do soil degassing campaigns from a safe distance and faster.”

Poás, located in the nation’s central region in Poás Volcano National Park and 25 miles northwest of the capital San José, has experienced frequent eruptions. Seismic activity and sulfur dioxide emissions have been increasing, and ground has uplifted in the area.

A March 1 steam-driven, or phreatic, eruption produced an ash column rising 1,000 to 1,300 feet. That was followed by several other eruptions.

“The challenge with phreatic explosions lies in their sudden occurrence, with little to no warning,” Girona said. “I hope using drones to measure soil degassing and soil conditions can help us to better anticipate these events.”

The flight into an active volcano was the first for ACUASI. The UAF team worked from a visitor platform one-third of a mile from the boiling summit crater and used two drones, one to look for a landing site for the gas sampling and the other to place the science instruments.

The mission began with a smaller drone, a 1-pound Parrot, scouting out a landing site for a larger drone carrying a small gas accumulation chamber, a gas sensor and a soil sensor. 

A 24-pound Alta X Heavy Lift drone arrived, with the Parrot remaining airborne while its camera showed pilots the Alta X’s activity.

The Alta X landed and shut down its rotors but remained powered. Springs above the accumulation chamber pressed it gently into the soil, where it remained for about two minutes. The drone then departed to gather measurements at the next location.

“The aircraft performed extremely well in the challenging environment of the volcano,” said Williams, ACUASI’s chief unmanned aircraft systems pilot.

“There were some challenges to overcome, mainly the difficulty in determining the height of the instrumented aircraft from the ground while performing the landing and the exact lateral position in relation to the desired landing spot,” he said.

Coordination was key, especially with a third drone — operated by Copple — flying nearby to provide height above ground information to the Alta X pilot.

“There was an enormous amount of crew coordination by all three pilots while attempting to land the instrumented drone in the crater,” Williams said. “Since all three aircraft were airborne and in close proximity to each other, we were constantly informing each other of our height and position.”

Girona called the mission a significant achievement. The drones performed their tasks and the sampling payload worked as intended.

“It demonstrates the feasibility of using our approach for remote soil degassing measurements in challenging environments,” he said. “The mission not only confirmed the viability of the technique but also provided critical experience that will enhance future deployments in similar volcanic environments.”

The team did see areas for improvement.

“With additional funding, we plan to refine and optimize our approach, expand fieldwork to different volcanic environments, and integrate advanced technologies to enhance measurement capabilities,” Girona said, adding that he expects to publish results from the Poás work.

View images at UAF

  drones, safety, uaf, volcano