Explosive trend: The supervolcano under the Phlegraean Fields near Naples is approaching a critical point – it could undergo a “regime change” as early as the 2030s, as volcanologists have determined. Accordingly, the increasing volcanic activity of the Campi Flegrei indicates self-reinforcing behavior. This could cause the supervolcano to reach a tipping point between 2033 and 2035, at which point the crust will give in to the growing pressure. However, it remains to be seen whether this “regime change” represents an eruption or just a change in activity.
The largest active supervolcano in Europe lies beneath the Phlegraean Fields near Naples. A good 39,000 years ago, this volcanic area caused the largest volcanic eruption on our continent, and other larger eruptions followed 29,000 and 15,000 years ago. Today, gas leaks, repeated weak earthquakes and uplifts of the subsoil show that the supervolcano beneath the Campi Flegrei is still active. In recent decades, activity has often temporarily increased, but then ebbed again after a few years.
A supervolcano awakens
But things now seem different: the supervolcano has been unusually active again since 2005 – and the trend is increasing. Measurements show increased emissions of volcanic gases, rising temperatures and increasing gas pressure. “The subsoil has since risen by more than 1.60 meters, accompanied by a noticeable intensification of shallow earthquakes,” report Davide Zaccagnino from the National Volcanological Institute in Rome and his colleagues. Geological data also suggest that magmatic fluids rise from the depths beneath the Campi Flegrei.
These observations suggest that something is happening beneath the Phlegraean Fields – and at an increasing pace. “Both the subsurface deformation and the seismicity show a clear and persistent acceleration,” said the volcanologists. But whether this heralds an eruption or just a temporary phase of unrest remains to be seen. It is therefore important to determine more precisely what form this acceleration takes, they explain. Because this could provide information about further developments and their causes.
Exponential or super-exponential?
For their analysis, Zaccagnino and his team examined which physical-mathematical function the accelerated activity of the supervolcano follows. Two variants would be conceivable: With an exponential acceleration, the activity of the Campi Flegrei increases at a fixed growth rate. “Such behavior already signals an unstable and unsustainable regime,” explain the researchers. However, it is not possible to tell when the situation will change.
This is different with a so-called finite-time singularity (FTS). With this super-exponential acceleration, positive feedback ensures that the growth rate also increases. The entire process escalates so quickly that a fundamental regime change occurs within a measurable time, as the volcanologists explain. In the case of a volcano, this can be an eruption, but also the transition to a new phase of rest or activity.
For the Phlegraean fields this means: If the current activity of the supervolcano follows such a super-exponential acceleration, the parameters of this function can be used to determine when the tipping point is imminent. “It is therefore crucial to distinguish between these two classes,” explain Zaccagnino and his colleagues. They have now investigated this using geophysical data and statistical methods.
Clear characteristics of self-reinforcing activity
The result: The activity pattern of the Campi Flegrei has shown a super-exponential development for a good 20 years. “The trend is better described by a singularity of finite time than by a simple exponential curve,” reports the team. This suggests that the current activity of the Phlegraean fields is characterized by positive feedback and is approaching a critical threshold.
Volcanologists see the reason for this as the progressive weakening of the earth’s crust due to the pressure of magmatic fluids rising from below. Because the crustal rock is stretched more and more and chemically weakened, it reacts more and more sensitively to further stress – a self-reinforcing process. “The system ‘remembers’ past deformations and each subsequent episode reduces the mechanical integrity of the crust even more,” explain the researchers. Until the point comes where she gives in.
Critical point between 2033 and 2035
But when is this tipping point reached? “Based on available information, regime change is likely to occur between 2033 and 2035,” report Zaccagnino and his colleagues. “If the current trend continues, the supervolcano will then enter a new dynamic phase.” According to their calculations, the earth’s surface above the Phlegraean Fields could have risen by more than four meters at this time.
However, it is unclear what exactly happens when the regime changes in the Campi Flegrei. It would be conceivable that there is a smaller, local eruption in a part of the area, through which some of the tension is released abruptly. According to volcanologists, a giving way and breaking of the crust or simply a largely inconsequential decrease in activity would also be possible.
Is there a threat of a major eruption?
However, the researchers emphasize that the tipping point does not mean that there will be another major eruption of the supervolcano in the 2030s: “Even if the system is heading towards a critical mechanical threshold, it is not in a phase of system-wide collapse,” they write. The damage to the crust and the earthquakes are localized and the typical features of an impending large eruption are missing.
Nevertheless, Zaccagnino and his colleagues strongly recommend continued close monitoring of the supervolcano and regularly updated forecasts. “This is necessary to support risk management in this densely populated and highly vulnerable region,” the team said. More than a million people live in the Campi Flegrei area and its edges.
Source: Davide Zaccagnino (Southern University of Science and Technology, Shenzhen/ Istituto
Nazionale di Geofisica e Vulcanologia, Rome) et al., preprint arXiv, 2026; doi: 10.48550/arXiv.2604.25204