There are an estimated 300 active volcanoes around the world. Monitoring them to forewarn the public is an important undertaking, but measuring volcanic gas emissions is not an easy feat. Recently, to aid this effort, researchers have designed specialized drones to watch and monitor an active volcano in Papua New Guinea.
Their findings can prove useful to local communities nearby volcanoes by forecasting impending eruptions while also benefitting scientists understand more about inaccessible active volcanoes and how they contribute to the global carbon cycle.
The focus of the team is the Manam volcano situated just off the northeast coast of mainland Papua New Guinea. About 9,000 people reside there, and it is among the most active volcanoes in the country.
Existing methods of prediction
Scientists already have certain methods available to predict volcano eruptions. One way of doing so is watching for seismic activity since eruptions are almost always preceded by high earthquake activity. Another way is looking out for bulges in the sloping walls of a volcano, which is caused by magma buildup underneath the outer layer.
Also, when the weather conditions are right, satellites can also measure a volcano's gas emissions, like sulfur dioxide (SO2).
Leader of the research, Emma Liu of College London told UCL News that Manam hasn't been studied in detail before. Tobias Fischer of the University of New Mexico added that they also wanted to quantify the carbon dioxide (CO2) emissions from this very large CO2 emitter.
When you put it into perspective, volcanic carbon emissions are a mere fraction of that originate from human activities, but researchers still want data to include it in our global carbon budget.
How it was done
The international team traveled to Papua New Guinea and put two long-range drones to test. These drones were equipped with cameras and gas sensors. The initial tests were conducted between October 2018 and May 2019.
The drones went up to 6,561 feet (2,000 mt) to monitor and sniff the volcano's turbulent volcanic plumes, about 3.7 miles (6 km) away from their launching spot.
Each flight saw drones snapping pictures of Manam's two craters, measuring gas composition above the plumes. They also bagged four bags of gas to be analyzed after the touchdown. These flyovers showed that the southern crater degassed more intensely over time between October 2018 and May 2019. In fact, it actually erupted later in June, one month after researchers finalized their second trip.
But intensified degassing is not a reliable indicator of whether a volcano is going to erupt. That's why researchers wanted to check if the ratio between CO2 and SO2 changed during this period of time. It was theorized that hot magma ascending towards the surface leads to a higher expulsion of CO2. The findings did not back this up, however.
Refining their data from drones with satellite imaging, the team demonstrated that Manam falls in the 10 biggest contributors to volcanic degassing with 3,700 tons of CO2 and 5,100 tons of SO2 every day. Carbon isotope analysis of the gases also showed that the emitted carbon likely originates from the upper mantle as opposed to Earth's shallower crust.