Think of a moka, the legendary coffee maker that many Italians still use every morning. Imagine filling it with water, putting the coffee grounds on top, and then sealing it hermetically over the stove. What happens? The pressure increases until the water, transformed into steam, finds an outlet through the filter. The Campi Flegrei, the immense volcanic caldera west of Naples, works exactly like this. And the seismic risk that has threatened half a million people (including me) for years could have a very different cause than previously assumed: not rising magma, but rainwater that accumulates in a sealed system.
Confirmation comes from a study published Science Advances which consolidates a theory already previously presented by the doctor Tiziana Vanorio, a Stanford researcher and originally from Pozzuoli. It is not the first time that the scholar has spoken out on this topic, but today we have published scientific data that support her theses. And if she is right, we could move from simple monitoring to active management of seismic risk.
I say this bluntly: it would be an epochal turning point for those who, like me, follow the evolution of this situation with a certain apprehension.
A closed system that builds up pressure
According to research conducted at Stanford University, what makes Campi Flegrei so dangerous is a surprisingly simple phenomenon: rain. Or rather, rainwater that infiltrates the ground until it reaches the underground geothermal reservoir, sealed by an impermeable surface layer (the so-called “caprock”).
This caprock has a peculiar characteristic: it is fibrous. In engineering, fibrous materials are used specifically for structural reinforcement because they can deform without immediately breaking. In a volcanic system, this means they can store tension for a long time, until an eventual sudden release through an eruption of superheated water, steam, and volcanic ash.
In Vanorio’s rock physics lab, researchers demonstrated how cracks in caprock seal through interactions between rock minerals and hydrothermal water and steam. To test the characteristics of caprock, they conducted experiments using a hydrothermal vessel that works just like a moka pot: They filled the lower chamber with brine and the upper one with volcanic ash and crushed rocks typical of the Campi Flegrei, then heated the vessel to the temperature of the geothermal reservoir. In less than 24 hours, mineral fibers formed and cracks in the rock layer quickly sealed.
Seismic risk, the truth is in the data
The analysis focused on two periods of recent seismic activity: that of 1982-1984 e the one from 2011 to 2024. In both cases, the earthquakes They started within the caprock, at a relatively shallow depth of about 1,6 km. As the co-author explains Tianyang Guo, analyzing the temporal evolution of earthquakes, a very clear pattern can be noticed: earthquakes become deeper over time.
This is crucial. If it were magma or its rising gases that caused the instability, we should observe the opposite: earthquakes that start closer to the deepest melting region (about 8 km below the surface) and become progressively shallower. Furthermore, rising magma without an eruption cannot explain the ground subsidence that follows periods of instability, adds the vain.
This seems to me to be an extremely sensible explanation for something that the inhabitants of Pozzuoli know well: the caldera “breathes”, spewing smoke and shifting the ground, sometimes meters up or down in a short time. After the 1982-1984 bradyseism, the area sank about a meter. For this to happen, there must be a release of mass from the subsurface, which can include magma, water, steam, and carbon dioxide.
The importance of precipitation
Researchers they examined 24 years of precipitation patterns, the directions of groundwater flow and the caprock sealing process to understand the geothermal reservoir recharge and subsequent pressure build-up.
To address the problem, we can manage surface runoff and water flow, or even reduce pressure by withdrawing fluids from wells.
These are the words of the professor vain, who (I remind you) is not only a geophysicist, but also a citizen with a goal: to demonstrate that instability can be managed, not just monitored, paving the way for prevention.
Think about the impact that such an approach could have. It's like moving from cure to prevention in medicine. Identifying risks before they manifest.
A new model for seismic risk management
This Stanford model, as mentioned, challenges a widely accepted theory: that bradyseism is driven by magma or its gases rising to shallower depths as melt from a deep melt zone moves upward into the subsurface beneath the volcanic area.
Analysis of tomography and the location and magnitude of earthquakes has contributed to the researchers' theory that the recurring tremors may not be driven by magma filling or gas emission from the system. One plausible explanation for the subsidence is the observed discharge of water and steam after the ground ruptures due to seismic activity, which naturally releases pressure inside the "reservoir."
The research data of Stanford supported by those of theUniversity of Naples Federico II, provide a convincing picture: we are not observing an unpredictable phenomenon, but a hydraulic system that could be managed with targeted interventions.
Campi Flegrei, seismic risk is manageable
The implications of this research are enormous. Instead of focusing exclusively on evacuation plans (which are still necessary), we might start considering preventative measures. Three in particular:
- Restore water drainage channels to reduce infiltration into the geothermal reservoir.
- Monitor groundwater levels more carefully.
- Withdraw fluids from wells to actively reduce pressure in the reservoir.
We are talking about interventions that, if implemented correctly, can potentially prevent or significantly reduce the intensity of the seismic swarms that have terrorized the population in recent years. Not to mention damage containment: in the last three years alone, many buildings have been damaged by the continuous tremors, and several families have lost their homes.
The perfect storm of geology
I really like how the vain he described the situation in the press conference where he anticipated the results of this study (I talked about it here): “I call it the perfect storm of geology: you have all the ingredients to have the storm: the burner of the system (the molten magma), the fuel in the geothermal reservoir, and the lid.”
We cannot act on the burner, but we have the power to manage the fuel. By restoring water channels, monitoring groundwater, and managing reservoir pressure, we can move Earth sciences toward a more proactive approach (much like preventative healthcare) to detect risks early and prevent problems before they arise.
Imagine the paradigm shift: from helpless victims of unpredictable natural forces to active managers of a system that, however complex, can be at least partly controlled. This is how science serves society.
A new chapter for the Campi Flegrei
The Campi Flegrei caldera is a 13 km wide volcanic area, a vast depression formed by major eruptions about 39.000 and 15.000 years ago, which caused the Earth's surface to collapse. But despite its explosive history, we may be able to live with it more safely.
The study does not suggest that the volcanic hazard has disappeared (the magma is still there, after all), but it offers a new perspective on how to manage the associated seismic risk, which is often the most immediate precursor to potential disasters.
For me, who has been following these developments for years, it would be like finally seeing the light at the end of the tunnel. It is not a magic solution, but it is a significant step forward in our understanding of one of the most dangerous volcanic systems in the world.
While authorities continue to discuss only evacuation protocols, perhaps it is time to start talking about active risk management. Because sometimes, the best response to a threat is not to flee, but to understand it well enough to manage it.
