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A volcanic plume rising over Mount Etna

Understanding Mount Etna Mount Etna is one of the most active and most comprehensively monitored volcanoes in the world, with hundreds of instruments on the surface providing terabytes of data on its activity. The Improve project team are investigating signals from the volcano and how they relate to magma dynamics, as Dr Paolo Papale explains. As one of the best monitored and also most active volcanoes in the world, Mount Etna is the ideal location to study the behaviour of magma below the earth’s surface and its impact on volcano dynamics. Several hundred instruments are permanently deployed on the surface of Mount Etna and in the surrounding area, which provide large volumes of data on the volcano’s activity. “We are capable of seeing even very small ground movements at Mount Etna, over hundreds of square kilometres in the surrounding area,” says Dr Paolo Papale, Research Director of the Italian National Institute of Geophysics and Volcanology (INGV). As coordinator of the Improve training network, Dr Papale is part of a team analysing data from Etna, in order to gain deeper insights into volcano dynamics. “We collect many different signals from multi-parametric instrumental systems placed on Mount Etna that record continuously in real-time,” he outlines. “We investigate those signals in order to understand them and to relate them to the dynamics of magma at depths.”

Signals from Etna A wide variety of signals are being considered in this research, including ground deformation and shaking, gas release and changes in gravity, which is related to movements of mass and variations in density. Historically, the study of ground motion around volcanoes has been divided into two disciplines, related to two extremes in terms of timescales. “One is the study of ground-shaking during earthquakes, which is very rapid, and is recorded with seismic instruments. The other is ground movements related to the inflation or deflation of the volcanic system, which occur over longer timescales. We record the deformation of the system over days, months, years, even decades,” explains Dr Papale. Between high frequency ground-shaking and very slow ground motion there is a large gap, which Dr Papale says is a major topic of interest

The IMPROVE early career researchers visiting the top of Mount Etna during the multi-parametric experiment in summer 2023.

characterise those signals. Alongside the permanent instrumentation on Mount Etna, this provides a wealth of signals for researchers to analyse and interpret, with the goal of building a fuller understanding of the volcano. “We want to understand how things happen, such as how magma is displaced and how it moves through different reservoirs in the volcanic system. What kinds of signals are then released?” explains Dr Papale. The ultimate aim is to develop the capability to accurately forecast eruptions, and protect the many

Instruments on Etna An effective and reliable forecasting system must be built on solid foundations, and so great emphasis is placed on scientific rigour in the project. By working with many different instruments and data sources, researchers are able to ensure their findings are robust. “We need to be careful in our research.

Positioning of an infrasonic sensor close to the top of Mount Etna for the multi-parametric experiment in summer 2023.

Mount Etna erupting. Photo by Boris Behncke.

in the project. “The numerical simulations that have been done suggest that ground movements in this hidden window can be very important,” he says. The focus of attention in the project is on this window, with researchers placing instruments on the volcano that are designed to record signals and gather data

millions of people across the world who live in close proximity to active volcanoes, yet Dr Papale says it remains difficult to interpret these signals.

That’s why we need to place so many different instruments and record so many different things,” says Dr Papale. Alongside experimental, numerical and physical studies, the project’s agenda also includes machine learning research, looking to identify similarities and differences between volcanic signals. “We are also working on automatic signal recognition through machine learning techniques, looking at both data from the volcano and synthetic data,” continues Dr Papale. “If we find some relevant similarities in the data, robustly rooted in the processes we are studying, then we can use numerical simulations to build a deeper understanding.” This can then help researchers identify where instruments should be placed in order to maximise their observational value and guide further investigation into volcano dynamics beyond the project. Strong relationships have been forged between the partners in Improve, which Dr Papale says will provide a kind of seed for the development of future research projects. “Improve is contributing to the establishment of a European community of volcanologists, and we will continue to work together in future,” he says. “We want to help create a strongly interconnected European research community.”

band, which represents a new dimension in the study of active volcanoes,” he outlines. The instruments, including infrasonic microphones, broadband seismometers, tiltmeters, high-speed visible and infra-red cameras, and prototypal high-frequency GPS receivers, were placed mainly in the upper part of Mount Etna, which

“We collect many different signals from multi-parametric instrumental systems placed on Mount Etna that record continuously in real-time, complemented by data from field experiments and by sophisticated numerical simulations. We aim at developing a more comprehensive understanding of magma dynamics leading to volcanic eruptions.” over the period between one minute and one day. The project team is conducting experimental, numerical and field work on ground movements over that period, which Dr Papale hopes will open up new perspectives in the study of active volcanoes. “We are bringing together researchers from several disciplines to try and understand the signals in this frequency

will help researchers learn more about volcano dynamics at shallow depths. “We concentrated the instruments in an array geometry in a comparatively small region close to the top to see signals from shallow depths in the volcano,” continues Dr Papale. This geometry allows researchers to accurately constrain the region from which the signals emanate and also to

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