Magma reservoirs identified in the Tuscan subsoil

Zero impact technology: seismic noise tomography

The result was obtained thanks to the use of environmental seismic noise tomography (Ambient Noise Tomography), a cutting-edge methodology that allows you to analyze the subsoil without drilling or explosions. “This is a method that allows the earth’s crust to be ‘x-rayed’ by exploiting the vibrations that are continuously generated by ocean waves, wind or human activities.“, explains Domenico Montanari, coordinator of activities for the Cnr-Igg. Through the installation of around 60 high-resolution sensors, the researchers detected unusually low wave propagation speeds, a characteristic signal of the presence of partially molten rocks and magmatic fluids.

Implications for the energy transition and raw materials

In Tuscany, the magmatic activity of the last million years has been predominantly plutonic, i.e. confined in depth without evident surface eruptive manifestations. “We knew that this region, which extends north to south across Tuscany, is geothermally active, but such large magma reservoirs were difficult to imagine. This discovery is extraordinary“, explains Matteo Lupi, associate professor at the Department of Earth Sciences of the Faculty of Sciences of the University of Geneva who led the study.

In addition to the purely scientific interest, the discovery has direct implications for the green economy. The precise identification of these heat sources allows the region’s geothermal potential to be quantified more accurately, offering a constant and renewable energy source. Furthermore, Deep magmatic systems are often associated with the formation of critical metals, such as lithium and rare earths. The possibility of using rapid and economical exploration techniques paves the way for a more efficient search for these resources, which are fundamental for the production of batteries and high-efficiency technologies.

“These results are important both for fundamental research and for practical applications, primarily for quantifying the geothermal potential of a region. In addition to their great scientific interest, these studies show that environmental seismic noise tomography, by exploring the subsurface quickly, at low cost and without any impact on the environment, can be a key tool for the energy transition“, concludes Gilberto Saccorotti (INGV).

Cover image: Conceptual model of the geothermal systems of Larderello, Travale and Monte Amiata. The areas in red surrounded by dashed lines correspond to anomalies in the speed of propagation of shear waves of at least 20%. These volumes are interpreted as accumulation zones of rocks in a partially molten state, with dimensions of approximately 6000 km³ and 2000 km³ for the Larderello-Travale and M. Amiata systems, respectively. The blue arrows indicate the ascent of fluids of magmatic origin towards the most superficial portions of the earth’s crust.