The research drone in action on the island of Vulcano at the southern boundary of the Aeolian Islands

Drone uses lightweight sensors to determine next volcano eruption

Image credit: Hoffmann group

A small drone equipped with ultra-lightweight sensor systems has been developed to monitor volcanos and improve predictions about when they might next erupt.

The main gases released by volcanoes are water vapour, carbon dioxide, and sulphur dioxide. Analysing these gases is one of the best ways of obtaining information on volcanic systems and the magmatic processes that are under way.

The ratio of carbon dioxide levels to those of sulphur dioxide can even reveal the likelihood of an impending eruption.

While drones have already been used to analyse the site of volcano activity, transporting them to their operation sites has required significant expense due to their high weight.

A team of researchers at Johannes Gutenberg University Mainz (JGU) has been assessing a very compact drone system that can be transported on foot to sites that are normally extremely difficult to access through other means.

A particularly promising parameter when it comes to the surveillance of changes to volcanic activity is the ratio of concentration of carbon dioxide to sulphur dioxide in the released gases.

The Little-RAVEN observation drone during a test flight in Mainz

Image credit: Hoffmann group

Alterations to this ratio have been observed immediately prior to eruptions of several volcanoes, including Mount Etna in Sicily.

Unfortunately, the practical side of compiling a continuous time series of gas compositions represents a major challenge. Direct manual sampling by means of climbing the volcano is arduous and time-consuming and could be dangerous should an eruption suddenly occur.

Stationary monitoring equipment often fails to record representative data on gas compositions, mainly due to changing wind directions.

Drones make it possible to reach emission sources that are otherwise difficult or even impossible to access, such as fumaroles in steep, slippery terrain or older parts of the plume that are typically located in downwind areas and at higher altitudes.

Only larger drones have so far been employed for the monitoring of volcanoes, which has proved problematic in view of the remoteness of the regions in which most volcanoes are to be found.

“It is for this reason that small, easily transportable drones are an essential prerequisite if we want to get to isolated or difficult-to-access volcanic sites and suitably track the activity there,” said Niklas Karbach, lead author of the research paper.

The research team has been trialling a tiny commercial drone weighing less than 900 grams equipped with miniaturised, lightweight sensors. This combination could be transported easily to the scene in a backpack.

“We need to obtain real-time data on sulphur dioxide levels as this lets us know when we are actually in contact with the volcanic plume, something that readily moves over time in response to atmospheric factors. The localisation of a plume by visual means alone from a distance of several kilometres is practically impossible,” said Professor Thorsten Hoffmann, head of the research team.

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