Using drones to monitor volcanoes.
Researchers analyze volcanic gases with the help of ultralight compact drones to identify the likelihood of an imminent eruption.
The main gases released by volcanoes are water vapor, carbon dioxide, and sulfur dioxide. The analysis of these gases is one of the best ways to obtain information on volcanic systems and magmatic processes in progress. The ratio of carbon dioxide to sulfur dioxide levels can even reveal the likelihood of an impending eruption. Drones, in this case, are used to transport the necessary analytical systems to the site of activity. However, due to their size, transporting the drones to operational sites has so far required significant expense. A team led by Professor Thorsten Hoffmann of the Johannes Gutenberg University of Mainz (JGU) recently assessed the potential of using a small and portable observation drone in remote regions. This very compact drone can be transported on foot even to sites that are difficult to access. Furthermore, it requires only minimal flight and administrative preparations to be used as an aerial observation platform.
The gas emissions released during eruptions are among the few chemical signals that provide evidence of the processes that take place in magmatic systems that are found at depth and are, therefore, inaccessible. Researchers have long believed that analyzing these volatile emissions could play a central role in improving the prediction of volcanic eruptions. A particularly promising parameter for monitoring changes in volcanic activity is the ratio of carbon dioxide to sulfur dioxide concentrations in the released gases. In fact, alterations of this relationship have been observed immediately beforeof the eruptions of several volcanoes, including Etna. Unfortunately, the practical aspect of compiling a time series of gas compositions presents a major challenge. Sampling is manual and direct via climbing the volcano. An arduous task that takes time, not to mention the potential dangers in case of a sudden eruption. On the other hand, stationary monitoring equipment often does not record representative data on gas composition, mainly due to the variation in wind direction. The drones measurement tools can overcome these problems and have already been used to measure the chemical characteristics of volcanic gases. In particular, the risk for volcanologists of being endangered by sudden changes in volcanic activity is greatly reduced by the greater distances traveled. Furthermore, drones allow reaching emission sources otherwise difficult or even impossible to reach, such as fumaroles on steep and slippery terrain or the older parts of the plume, typically located in leeward areas and at higher altitudes.
So far, only large drones have been deployed for monitoring volcanoes and of course this has proved problematic given the remoteness of the regions where most of the volcanoes are found. “That is why small and easily transportable drones are an essential prerequisite if we are to reach isolated or difficult-to-access volcanic sites and adequately follow their activity,” said Niklas Karbach, lead author of the article recently published in Scientific Reports.
A small drone that can be carried in a backpack
In collaboration with the volcanologist Nicole Bobrowski of the University of Heidelberg and with the National Institute of Geophysics and Volcanology (INGV) in Catania, the research team from Mainz tested a small commercial drone weighing less than 900 grams , equipped with miniaturized and lightweight sensors. This combination, which weighs no more than a bottle of mineral water, could easily be carried on site in a backpack. But it’s not just the weight of the drone that’s crucial. “We need to get real-time data on sulfur dioxide levels, because this lets us know when we are actually in contact with the volcanic plume, which moves easily over time in response to atmospheric factors. Localizing a plume by visual means alone from a distance of several kilometers is practically impossible,” added Professor Hoffmann, JGU team leader.
The goal of this project, which sees the collaboration of researchers from Mainz, Frankfurt, Heidelberg and Munich, is to understand the connections between magmatic processes in the Earth’s mantle and the atmosphere, combining the skills of different disciplines such as experimental petrology and atmospheric chemistry.