Campi Flegrei, the National Research Council (CNR) raises the alarm: "Stronger tremors are not ruled out."

Naples – The Campi Flegrei area continues to tremble, and uncertainty about the evolution of the bradyseismic crisis remains high. After the violent 4.7 magnitude tremor recorded between Pozzuoli and Quarto, experts are urging caution but are not shying away from the complexities of the phenomenon.

“It is possible that the seismic swarm will continue in the next few hours or days, but it is not possible to predict its duration, number, or magnitude of the tremors, nor can we absolutely rule out exceeding the current record,” explained Andrea Billi, a researcher at the CNR Institute of Geosciences (CNR-Geo).

A seismic record for decades and the update on the alert

The seismic event is the most energetic ever measured instrumentally in the Phlegraean Fields area in several decades, even exceeding the historical peaks reached during the 1982-1984 crisis (when the strongest tremors of 1983 and 1984 stopped at magnitude 4.0).

Due to the shallow hypocentral depth—just 3 kilometers—the earthquake was clearly felt not only at the Phlegraean epicenter, but also in Naples, Ischia, and as far as the Sorrento peninsula.

However, experts advise against panic:
"A single earthquake does not, in itself, indicate the imminence of a volcanic eruption. Currently, the official alert level remains yellow. It is therefore essential to follow the communications from the Civil Protection Department and the monitoring agencies," Billi specifies.

Bradyseism: a centuries-old phenomenon

The earthquake is part of a broader process of bradyseism—the slow uplift and subsidence of the ground—that has characterized the Phlegraean caldera for centuries, traces of which are visible even on the columns of the Serapeum in Pozzuoli.

After approximately twenty years of ground subsidence, a new phase of uplift began in 2005 and is still ongoing. While during the crises of the 70s and 80s, the ground rose by a total of approximately 3,5 meters, triggering thousands of tremors, the current magnitude still represents an unprecedented peak.

What's happening underground

But what is the scientific cause of these tremors? The phenomenon is linked to pressure and temperature variations in the complex underground hydrothermal and volcanic system.

Ground uplift is caused by the accumulation and migration of water, steam, carbon dioxide, and other gases at high pressure, possibly with magmatic contributions from greater depths. When the accumulated stress exceeds the mechanical strength of the rocks, they fracture, releasing energy that propagates in the form of seismic waves.