Beneath Tuscany lies 6,000 cubic kilometers of hot magma, according to new European research using a remote-sensing technique that explores the subterranean environment with ambient sound.
Researchers from the University of Geneva (UNIGE), the Institute of Geosciences and Earth Resources (CNR-IGG), and the National Institute of Geophysics and Volcanology (INGV) published their work in Communications Earth & Environment, revealing a new application of ambient noise tomography to identify important subterranean resources such as geothermal reservoirs, lithium, and rare earth elements.
The new technique enables faster, more cost-effective discovery of magma-related resources crucial to modern technology, such as battery and superconductor production.
Ambient Noise Tomography
Tomography is a remote sensing technique that uses various types of waves, such as X-rays or ultrasound, to pass through matter. By measuring how the waves are absorbed or scattered, these noninvasive techniques can generate 3D models of a solid object’s interior.
The collaboration’s tomography technique, known as ambient noise tomography, uses any ground vibrations other than earthquakes as the sensing wave, which is measured and analyzed with high precision to produce a subterranean 3D model. These minor vibrations originate from ocean waves, wind, or even human activity. The UNIGE team utilized about 60 above-ground sensors for the study, collecting high-resolution vibratory signals.
When those vibrations propagate at abnormally slow speeds, it reveals the presence of molten material hidden beneath the ground. With ambient noise tomography, magma deposits as deep as 15 kilometers below the surface can be detected without any above-ground indicators.
Identifying Hidden Magma
Using the technique, the researchers have already identified a massive magma reservoir under central Italy’s Tuscany region. While the west of Italy is known to harbor major volcanic activity, this is the first time such reservoirs have been identified in central Italy, despite some suspicions that such deposits may exist. No volcanic eruptions are known to have occurred in the region during the Holocene period, which spans the last 11,700 years, further adding to the uncertainty.
Some of Earth’s most well-known volcanic hot spots include Lake Toba in Indonesia, Lake Taupo in New Zealand, and Yellowstone National Park in the United States, each of which sits atop a massive magma reservoir. Major surface activity at these sites leaves behind clear signs recognizable to geologists, such as gas emissions, ground deformations, craters, and eruptive deposits. Without such obvious evidence of volcanic surface activity, though, locating hidden subterranean magma deposits can be extremely challenging.
Tuscany is an example of this type of well-hidden reservoir of molten rock. The roughly 6,000 cubic kilometers of magma extend from about eight to fifteen kilometers below the surface. The site’s primary discovery was by the UNIGE researchers, working with contributions from IGG-CNR and INGV. Presently, researchers say the magma poses no danger to the surface, but over immense geological timescales, it could eventually form a supervolcano.
Surprising Magma Find
“We knew that this region, which extends from north to south across Tuscany, is geothermally active, but we did not realize it contained such a large volume of magma, comparable to that of supervolcanic systems such as Yellowstone,” said lead author Matteo Lupi, associate professor in the Department of Earth Sciences at UNIGE’s Faculty of Science.
The development is a major breakthrough in reducing the cost and time sink associated with searching for some of modern technologies’ most important foundational resources, such as lithium and rare earth elements, which are closely linked to deep magmatic systems.
“These results are important both for fundamental research and for practical applications,” Lupi concluded, “such as locating geothermal reservoirs or deposits rich in lithium and rare earth elements, which are used, for example, in electric vehicle batteries.”
“In addition to their great scientific interest, these studies show that tomography, by exploring the subsoil quickly and at low cost, can be a useful tool for the energy transition,” he added.
The paper, “High-Enthalpy Larderello Geothermal System, Italy, Powered by Thousands of Cubic Kilometres of Mid-Crustal Magma,” appeared in Communications Earth & Environment on April 15, 2026.
Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org, and follow him on Twitter @mdntwvlf.