Discovering the Unbelievable: A Vast Roman City Submerged Beneath the Ocean
A thick cloud of grey-white steam rose about 30 meters away from where I stood. The ground went from cold and solid to hot and unstable as I looked toward it. It was important to stay away from the exact spot where this change happened. My guide for the day, volcanologist Ezo Morra, began climbing the hill on the other side of the wooden path as soon as we arrived.
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I stepped onto a wooden plank and then onto solid ground. It felt cool under my feet. As I climbed the hill, I saw where the steam was coming from: a big pool of dark gray mud. It looked eerie, like something from a witch’s potion, and it was making a lot of noise. The air smelled strongly of sulfur.
Morra stressed how risky it was there when I arrived. He said it was even riskier than being near Vesuvius. Campi Flegrei, also called the Phlegraea Fields, is one of the 20 known “supervolcanoes” on Earth. I was a bit slow to catch on to what “supervolcanoes” meant. I wondered why he hadn’t warned us when we were still over there, instead of waiting until we were here.
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We looked down into one of Campi Flegrei’s fumaroles, which is part of a supervolcano. This type of volcano can erupt with a force much stronger than a regular one, thousands of times over. Even though it’s overshadowed by Mt Vesuvius just 30km away, Campi Flegrei isn’t as famous, mainly because it hasn’t erupted in a big way recently. But if it did, it could be much more destructive than the eruption of Mt Vesuvius in 79 AD, which destroyed Pompeii. However, Campi Flegrei hasn’t had a major eruption in thousands of years.
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That doesn’t mean it can’t happen. Scientists call this supervolcano “restless,” and there are signs it’s becoming more active. In 2012, the alert level was raised from green to yellow, which means they need to watch it more closely. And in April 2020, there was a “seismic swarm,” which means there were 34 earthquakes in the area.
Campi Flegrei isn’t just a sleeping danger. That’s why the ancient Romans chose to build one of their best resort towns here: Baiae. It was famous for its hot springs and beauty.
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This constant movement in the earth is exactly why every bit of this historical site is at risk today. The artifacts face direct danger from the sea, and there’s also the looming risk of earthquakes or volcanic eruptions.
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Back in Roman times, they didn’t have ways to foresee eruptions or earthquakes. They also struggled to protect their town from the advancing sea. But today is different. A group of archaeologists and engineers is using new methods to save the site for the future. That’s why I’ve come here—to learn about these efforts and see how they work.
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Campi Flegrei is where you’ll find Baiae, an ancient Roman resort town known for its hot springs and gases. This supervolcano has 24 craters and over 150 pools of bubbling mud spread across its 13km area, some even under the sea. The early Greeks called it “Phlegraea Fields” because of its fiery nature.
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Campi Flegrei is not just big and powerful; it’s also unpredictable. Unlike Vesuvius, where eruptions usually start at the top cone, Campi Flegrei doesn’t follow such a pattern.
“The activity doesn’t stick to one spot,” Morra explained. “Each eruption happens differently, in a new place each time. That’s why we can’t predict when or where the next one will happen.”
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Another danger comes from how it erupts: more than 90% of the eruptions are explosive and strong. Instead of lava flowing on the ground, Campi Flegrei shoots out a mix of rocks and lava high into the air. After it falls back down, the ash makes the sky dark, making it hard to see and breathe. When the column collapses, it causes a pyroclastic flow, a super hot wave that burns everything it touches.
