The holiday hotspot of the Campi Flegrei area, near Naples, Italy, experienced a seismic swarm with 150 earthquakes tremors in one day, causing significant concern among residents.

The strongest quake, with a magnitude of 4.4, occurred at 8.10pm, following an earlier 3.5 magnitude quake. This marks the most powerful seismic activity in the region in the last 40 years.

As a result, 39 families living in buildings between the cities of Pozzuoli and Bacoli were evacuated as a precaution due to the persistent tremors and resulting damage. Many locals, fearing building collapses, spent the night outdoors but returned home as temperatures dropped at dawn.

Bacoli resident, Lucilla Schiano di Cola, told Express.co.uk: “The first tremor took me by surprise, I was working from home, at first I didn’t understand what was happening.

“The second one was terrible, I expected it but I didn’t foresee the intensity, I was alone at home and I was so scared, everything was moving, this time even the floors. After the third tremor, I packed my bags to be ready to run away. I didn’t sleep all night.”

The Vesuvius Observatory identified the epicentre of the strongest quake near the Solfatara in Pozzuoli. The tremors were felt in Bacoli, Monte di Procida, and various neighbourhoods in Naples, including Fuorigrotta, Bagnoli, Soccavo, Pianura, and the city centre, causing widespread alarm.

Monte di Procida resident, Luisiana Russolillo told Express.co.uk: “I didn’t feel the first two earthquakes because I was in the port area of ​​the town. But I saw people running out of their homes and into the street.

“During the third tremor, I was at home. Out of fear I packed a bag with the necessary things, grabbed my dog and ran into the street. A friend of mine slept in her car with her newborn baby for precaution. We were all very scared.”

Since the resumption of bradyseism — a phenomenon where the ground slowly rises and falls — in the early 1980s, the recent 4.4 magnitude quake surpassed the previous high of 4.2 recorded on September 27, 2023. Both incidents shared common characteristics: a depth of three kilometres and an epicentre near the Solfatara volcanic area.

Significant tremors included the 3.5 magnitude quake at 7.51pm and the 4.4 magnitude quake at 8:10pm, followed by less intense quakes at 9.31pm (2.4 magnitude), 9:46pm (3.9 magnitude), and 9.55pm (3.1 magnitude).

“These are strong and frequent tremors. I understand your fears. Therefore, I have immediately convened the Municipal Operations Centre to address any critical issues caused by the recent bradyseism tremors. I have decided to close all schools, public and private, in Bacoli as a precautionary measure to conduct necessary inspections,” Bacoli’s Mayor, Josi Gerardo Della Ragione, announced on Facebook. 

Bradyseism, described as “like the earth opening up,” is not unfamiliar to the residents of Pozzuoli and the wider Campi Flegrei area, which stretches from the coast to the neighbourhoods of Pianura, Soccavo, and Fuorigrotta in Naples.

The region sits atop a 12-kilometre caldera, with six kilometres extending under the Gulf of Pozzuoli and another six kilometres underground. Unlike the conical shape of Vesuvius, this ancient volcano formed tens of thousands of years ago.

The area has experienced periods of bradyseism, notably between 1970 and 1972, and again from 1982 to 1984, causing significant land uplift. In 1970, due to increasing instability, the Rione Terra area was evacuated.

A few days earlier, an emergency plan was enacted: Plan A involved evacuating the lower part of Pozzuoli, while Plan B entailed evacuating the entire town. Bradyseism has always been accompanied by seismic swarms of varying intensity. Since 2005, the area has been in a new phase of bradyseism, known as ascending bradyseism.