Scientists monitor active volcanoes by drones

But increased volcanic emissions are not a reliable indicator of whether an eruption is imminent on its own, therefore, researchers will also observe the ratio of carbon dioxide to sulfur dioxide in Manam's ash plume.

This could help monitor magma rising to the surface, as well as the carbon-rich emissions that erupt before big eruptions.

However, the researchers found that the structure of the gases emitted from Manam volcano was similar to the one during the two field trips.

Combining their drone measurements with satellite data, the researchers were able to prove that Manam is one of the top 10 most degasified volcanoes in the world, emitting about 3800 tons of carbon dioxide and 5100 tons of sulfur dioxide everyday -- more than previously expectation.

By analysing the different carbon isotopes in the gaseous mixture, the team inducted reasoning that most of the carbon emitted by Manam might have come from the upper mantle, rather than deposits in the earth's shallowing crust.

The research team concluded in the paper, “Our new approach – using long-range, high-altitude drones for field measurements -- is the only currently available method that allows us to analyse the gas chemistry of a steep, dangerous and highly active volcano like Manam.”

Research in the future will require more effort by scientists and longer flying time of drones, as this study measured data over a span of just 10 days.

If there are adequate equipment and training for local scientists, the method could be used elsewhere to monitor other dangerous unreachable volcanoes, such as Mayon in the Philippines and Sinabung in Indonesia.