Nestled beneath the picturesque landscapes of southern Italy lies a geological giant with a tumultuous past and an unpredictable future. The Campi Flegrei caldera, often overshadowed by its more famous neighbor Mount Vesuvius, has recently captured the attention of scientists and residents alike. A series of earthquake swarms in March 2025 has reignited concerns about the potential for a significant volcanic event, especially given the caldera’s proximity to the densely populated city of Naples.
Understanding the dynamics of Campi Flegrei is not just a matter of scientific curiosity; it’s a pressing concern for public safety. With over a million people living within its potential impact zone, the stakes are high. Monitoring and preparedness have become paramount as experts analyze the latest seismic data to assess the risks and forecast possible scenarios.
Understanding Campi Flegrei
Campi Flegrei, translating to “Burning Fields,” is a vast caldera encompassing approximately 13 kilometers in diameter. Formed over 39,000 years ago during a cataclysmic eruption, it is one of the most significant volcanic features in Europe. Unlike the conical structure of Mount Vesuvius, Campi Flegrei’s caldera is a depression resulting from the collapse of land following massive eruptions.
The region is characterized by numerous volcanic features, including craters, fumaroles, and hot springs. Its geothermal activity is a constant reminder of the molten forces beneath the surface. Historically, Campi Flegrei has experienced several eruptions, with varying degrees of intensity, shaping the landscape and influencing human settlement patterns.
The 1538 Monte Nuovo Eruption
The most recent eruption of Campi Flegrei occurred in 1538, leading to the formation of Monte Nuovo, a new mountain that emerged over a week-long period. This event was preceded by noticeable ground uplift and seismic activity, similar to current observations. While the 1538 eruption was relatively small compared to prehistoric events, it serves as a critical reference point for understanding the caldera’s behavior.
Since then, the region has remained volcanically quiet, but not geologically inactive. Periods of ground uplift, known as bradyseism, have been recorded, notably in the 1980s, causing significant concern and leading to temporary evacuations. These episodes underscore the caldera’s potential for sudden and disruptive activity.
Recent Seismic Activity
In March 2025, Campi Flegrei experienced an alarming increase in seismic activity, with over 200 earthquakes recorded in a 48-hour period. The most significant tremor reached a magnitude of 4.4, the strongest in the area in recent decades. These earthquakes were primarily shallow, indicating movement of magma or hydrothermal fluids beneath the surface.
This swarm of earthquakes is not an isolated incident but part of an ongoing pattern of unrest. Scientists have noted that the frequency and intensity of these events have been escalating, suggesting that the caldera is entering a more active phase. Continuous monitoring is essential to determine whether this activity will culminate in an eruption or subside over time.
Ground Deformation and Bradyseism
Accompanying the seismic activity is a phenomenon known as bradyseism, characterized by gradual ground uplift. Measurements indicate that the ground in certain areas of the caldera is rising at a rate of approximately 2 centimeters per month. This deformation is caused by the accumulation of magma or pressurized fluids beneath the surface, exerting upward pressure on the overlying rock.
Bradyseism poses significant risks to infrastructure, as the uneven ground movement can damage buildings, roads, and utilities. Moreover, it serves as a potential precursor to volcanic eruptions, making it a critical parameter in volcanic monitoring. The current rate of uplift is reminiscent of the 1980s bradyseismic crisis, which, although it did not lead to an eruption, caused widespread disruption and anxiety.
