High-enthalpy Larderello geothermal system, Italy, powered by thousands of cubic kilometres of mid-crustal magma
Thousands of cubic kilometers of magma lie in the upper crust below supervolcanoes such as Yellowstone (USA), Toba (Indonesia), and Taupo (New Zealand). Most of these systems are identified because of surface geomorphology and eruptive deposits. Recognizing such volcanoes without surface evidence is challenging, causing large magmatic reservoirs to go unnoticed. The Tuscan Magmatic Province, Italy, features only sparse Quaternary volcanic activity, but subsurface data indicate the presence of supercritical fluids at shallow depths. Here we show that more than 5'000 km3 of magma and partial melt are stored in the middle crust of the Tuscan Magmatic Province, Italy. This fuels the high-enthalpy geothermal systems of the region. Such volumes are comparable to those of mid-crust reservoirs beneath recognized supervolcanoes. The discovery of large volumes of magma is critical to explain the long-term evolution of mature magmatic systems and to understand the behavior of large magmatic provinces.
Mud volcanism and creepy mud flows: A new model
Mud volcanism is a widespread geological phenomenon characterized by spectacular mud flow deposits extending for kilometers. However, only a few eruptive events have been reported to be long-lasting and voluminous enough to create such extensive flows. We report findings from a multidisciplinary investigation conducted after three eruptions occurring since August 2022 at the Lokbatan mud volcano in Azerbaijan. During these three short-lived events, only a moderate volume of mud breccia was expelled around the crater site. However, field observations show that these events promoted the downslope motion of the >1-km-long older mud flow. Electrical tomography reveals a conductive unit at ∼25 m depth below the volcano, which lubricates the detachment upon which sediments slide. Cross-checking legacy satellite imagery (from 2009) combined with InSAR data (from 2014) reveals that this type of movement was already occurring as early as 2009, indicating a long-lasting process. Our findings suggest that kilometer-sized mud flows observed at other mud volcanoes may not stem from single, voluminous eruptions, as previously thought, but from gradual sliding processes initiated by new loads of erupted material. This mechanism is essential for understanding the dynamics of mud volcanoes on Earth.
Melt, fluids, and fractures beneath Ebeko Volcano (Kuril Islands) revealed by ambient noise attenuation tomography
The northern part of Paramushir Island (Kuril Arc) is dominated by the NNE–SSW oriented Vernadsky Ridge that hosts the presently active Ebeko Volcano, where phreatomagmatic eruptions coexist with complex hydrothermal activity. We apply ambient noise attenuation tomography (ANAT) to seismic data from a 21-station network, revealing three-dimensional attenuation structures. Key findings include: (1) Shallow high-attenuation anomalies (Qc−1 > 0.45 at 0.5–2 km depth) beneath Ebeko's craters and Yuriev hot springs, mapping fracture-controlled fluid reservoirs; (2) A 4–6 km deep low-attenuation core (Qc−1 < 0.1) surrounded by high-attenuation zones, suggesting a magmatic storage region with radial fluid pathways; and (3) A progressive north-to-south decrease in attenuation (Qc−1 > 0.45 to < 0.15) that mirrors the Vernadsky Ridge's volcanic evolution from extinct southern edifices to the currently active Ebeko in the north. These results illuminate how seismic attenuation patterns track both active fluid pathways and volcanic system maturation in arc environments.