Giant Magma Chamber Discovered Beneath Tuscany
A Swiss-Italian research team has identified a massive magma reservoir containing between 5,000 and 6,000 cubic kilometers of molten and partially molten rock beneath southern Tuscany.
The reservoir is situated at depths ranging from 8 to 15 kilometers (4.97 to 9.32 miles) below the surface, with a significant concentration beneath geothermal regions including Mount Amiata and Larderello. According to a study published April 14, 2026, in Communications Earth & Environment, the volume of this system is comparable to the magmatic reservoirs found beneath global supervolcanoes such as Yellowstone in the United States, Lake Toba in Indonesia, and Lake Taupō in New Zealand.
Seismic Mapping of Hidden Magma
Unlike the iconic volcanic sites mentioned above, the Tuscan region has lacked obvious surface indicators of such a large system, such as craters, eruptive deposits, or significant gas emissions. Because no major eruptions have been recorded in modern times, the reservoir remained hidden until the application of ambient noise tomography.
Lead author Matteo Lupi and his colleagues utilized natural ground vibrations to map the Earth’s crust, analyzing seismic data from more than 60 broadband stations. This included data from a temporary deployment active between September 2020 and September 2021. By reconstructing a 3D shear-wave velocity model, the researchers identified a prominent anomaly beneath the Radicondoli and Larderello geothermal districts, where shear-wave velocities dropped to approximately 1.25 km/s at a depth of about 10 kilometers.
These low velocities are typically associated with magmatic fluids, high temperatures, or partial melt. Lupi stated that while the region was known to be geothermally active, the scale of the magma volume was previously unrecognized.
Geothermal and Mineral Implications
The discovery provides a structural explanation for why the Tuscan geothermal province is one of Europe’s most productive high-enthalpy systems. The region is home to the Larderello power plant, the oldest geothermal power plant in the world, which relies on the intense heat flow sustained by the deep melt system.
Beyond the understanding of geothermal energy, the research team from the University of Geneva (UNIGE), the National Institute of Geophysics and Volcanology (INGV), and the Institute of Geosciences and Earth Resources (CNR-IGG) noted that the findings have practical applications for resource extraction. The formation of rare earth elements and lithium is closely linked to deep magmatic systems, and this mapping technique may allow for faster, more cost-effective exploration of these minerals.
The researchers clarified that the identification of the mid-crustal reservoir does not present evidence of current volcanic unrest.
The findings establish a new framework for identifying hidden magma systems in regions lacking surface volcanic signals, focusing on the correlation between deep magmatic volumes and the presence of geothermal reservoirs and mineral deposits.