In southern Italy, a vast volcanic region called Campi Flegrei has been shaking with frequent earthquakes since 2022.
This volcanic area, also known as the “burning fields,” is located west of Naples and covers the town of Pozzuoli.
Campi Flegrei is not a typical volcano with a towering peak. Instead, it is a massive caldera—a large, sunken area formed by volcanic eruptions thousands of years ago.
Over time, the ground in this region rises and falls, causing buildings to crack and local residents to worry about the possibility of a major eruption.
The last big episode of unrest happened in the early 1980s, leading to the evacuation of 40,000 people from Pozzuoli. Now, with the land shaking again, scientists have been working hard to understand what drives these movements.
For many years, experts believed that magma—molten rock—rising closer to the surface was the main cause of the ground swelling and the earthquakes.
But new research led by scientists at Stanford University suggests a different story. They discovered that water, not just magma, plays a huge role in triggering these quakes.
Through advanced imaging techniques and experiments in their lab, the researchers found that water and steam trapped beneath Campi Flegrei build up pressure over time. When the caprock, a thick layer of rock that acts as a lid, seals tightly, the pressure increases until the rock cracks, causing earthquakes and bursts of steam.
The study, published in Science Advances, explains that this process is like what happens inside a moka pot, the traditional Italian coffee maker. Just as steam pressure builds up under the lid of the pot until it bursts through, the same kind of buildup happens underground in Campi Flegrei.
The researchers even used a hydrothermal vessel filled with volcanic ash and brine in their experiments to mimic the conditions beneath the caldera. The findings revealed that managing water pressure might help reduce the risk of earthquakes.
Tiziana Vanorio, the study’s lead author and a professor at Stanford, grew up in Pozzuoli and was forced to evacuate during the 1980s unrest. Now, she is determined to use her research to help her hometown.
According to Vanorio, one key to controlling the shaking is to manage water flow and groundwater levels. By doing this, the pressure beneath the surface could be reduced, preventing the earthquakes that have caused so much damage. She believes that this method could help manage the volcanic system rather than just monitoring it.
The research team found that the land at Campi Flegrei “breathes,” moving up and down as water fills and drains from the underground reservoir. During heavy rainfall or periods of high groundwater recharge, water seeps into the ground and adds to the pressure. When the pressure builds up too much, the ground swells, and earthquakes happen.
If the pressure is released through cracks, the land settles back down, a process known as subsidence. This cycle has been going on for decades, but now researchers understand the role of water more clearly.
The research challenges long-standing beliefs that magma movements alone cause the ground to rise and fall. The team’s imaging of the subsurface showed that the recent swarms of earthquakes started at a shallow depth of about one mile.
If magma were the main driver, these quakes would begin much deeper, around five miles underground, and gradually move upward. Instead, the opposite happened, suggesting water pressure is the main trigger.
Vanorio believes that with proper water management, authorities could reduce the risk of major quakes in Campi Flegrei. The solution involves restoring water channels, controlling groundwater levels, and even draining water from wells to relieve pressure. She compares it to preventive health care: if you catch the problem early and manage it, you can avoid bigger issues. Her goal is to turn this research into a practical plan to protect the people of Pozzuoli and beyond.
The hope is that by better understanding how water pressure drives earthquakes at Campi Flegrei, scientists and local authorities can work together to prevent disaster before it happens.
For the people living atop this restless volcanic field, it could mean greater safety and peace of mind in the future.
