Santa Fiora, Tuscany, Italy
The reservoir is comparable to that of large volcanic regions such as Yellowstone or Taupō, but there are no historical records of eruptions.
A new published in the journal Communications Earth & Environment reports the discovery of a vast underground reservoir of magma under the region of Tuscany, in Italy.
The research, led by the University of Geneva in collaboration with Italian institutions, reveals that between 8 and 15 kilometers below the surfacethere is a huge mass of molten rock and superheated fluids. Estimated at more than 5,000 cubic kilometers in volume, the reservoir rivals the upper magmatic systems of large supervolcanoes, such as the Yellowstone Caldera in the United States.
Despite its size, the system has continued to exist undetected until now due to lack of visible volcanic activity. Unlike Yellowstone, which is marked by geysers, hot springs and gas emissions, Tuscany has only limited geothermal signs on the surface, hiding what researchers describe as a “silently dormant” magmatic structure.
The discovery was made using seismic tomography, a technique that analyzes the shape how seismic waves propagate through the Earth’s crust. By deploying a network of seismometers across the region, scientists were able to build a detailed model of the upper 15 kilometers of the Earth’s crust, revealing the presence and scale of the magma reservoir.
Although Tuscany was already known for its geothermal activity, the colossal size of the magma mass it was a surprise. Researchers say the system is comparable not only to Yellowstone, but also to other large volcanic regions, such as the Taupō Volcanic Zone and the Long Valley Caldera, all of which have a history of massive eruptions, explains .
However, Tuscany presents a geological mystery: there is no known record of eruptions connected to this reservoir. Scientists suggest that magma may remain trapped in the crust, forming partially molten zones rather than rising to the surface. Under these conditions, temperatures in the upper layers could exceed 500 °C, creating so-called supercritical fluids.
In addition to its scientific importance, the discovery may have practical implications. The presence of a system like this can help identify geothermal energy resources and deposits of valuable materials such as lithium and rare earth elements, essential for technologies such as electric vehicle batteries.
