The Campi Flegrei (the Phlegraean Fields) area in Italy is no stranger to volcanic activity. One of the largest eruptions in the area took place around 40,000 years ago, covering the area in ash and blasting open a caldera 9 miles wide. 

A recent study in Communications Earth and Environment discusses another massive volcanic eruption that occurred in the area 109,000 years ago, known as Maddaloni/X-6. However, this area is now inhabited by about 400,000 people, and with an uptick in seismic activity, understanding this volcano is now more important than ever. 

Will Campi Flegrei Erupt Again? 

According to a May 2025 Nature Communications study, the Campi Flegrei caldera has been stirring for the last 75 years. The last time there was an eruption was 1538, and according to historical records, the activity leading up to the eruption, rapid ground uplifting, is similar to the activity seen today. However, this may subside without an eruption. 

The 1538 eruption was relatively small compared to the massive eruptions of the past. On the VEI scale, the 1538 eruption was rated a 3, while the Maddaloni/X-6 eruption has been rated at a 7, according to the Communications Earth and Environment study. 

Though there is no way to predict if or when there will be a volcanic eruption, it’s likely that we won’t see a massive volcanic eruption like those of the past within our lifetime. However, there are teams working to better understand the inner workings of this volcano so that we can be as prepared as possible. 

Read More: Magma Beneath Yellowstone Appears to be on the Move

Understanding the Volcanic Region

Campi Flegrei is one of the most studied volcanic regions on the planet. Yet, there is still so much more to learn about it. 

Thanks to the new study, the research team used high-resolution seismic imaging and rock physics experiments on samples from the caldera’s deep wells to reconstruct an image of the internal structure. 

From these images, the team pinpointed three key structures that work “in tandem in controlling the distribution of microseismicity and ground deformation,” the study authors wrote in the article. 

These structures include a protective, fibrous caprock layer just below the surface. Under that is a gas-enriched reservoir, which is filled with water and steam. This reservoir acts like the lungs of the caldera and slowly builds pressure as liquids accumulate. The bottom is the dense, stable basement, which has a “carbonate-rich formation that dips toward the center of the volcanic system,” according to the article. 

From the Nature Communications study, the research team determined that the unrest is likely due to fluid buildup, rather than magma.

Better Monitoring of Campi Flegrei

The more experts know about this volcanic area, the better prepared they can be in the event of an eruption. The new information from the Nature Communications study provides researchers with a clearer understanding of what causes volcanic activity and unrest. It can also help determine if there is a greater risk to the public or if the activity is being driven by a force, like fluid, instead of magma. 

A research team, some of whom also worked on the Nature Communications study, has investigated methods to mitigate groundwater levels and water flow that may end up in a volcanic reservoir to reduce seismic activity also. 

“As scientists continue to map the subsurface of Campi Flegrei, each new discovery brings us closer to understanding the hidden forces shaping this ancient caldera – and what it might mean for the future of one of Europe’s most densely populated volcanic regions,” the study authors write in the article.

Read More: 5 of the Most Explosive Volcanic Eruptions

Article Sources

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A graduate of UW-Whitewater, Monica Cull wrote for several organizations, including one that focused on bees and the natural world, before coming to Discover Magazine. Her current work also appears on her travel blog and Common State Magazine. Her love of science came from watching PBS shows as a kid with her mom and spending too much time binging Doctor Who.