In recent days, the Phlegraean Fields have gained significant national attention due to the seismic swarm affecting the area. In this article, we will explore what the Phlegraean Fields are, their geographical location, their connection with Mount Vesuvius, and the recent seismic events.
We will also discuss the measures adopted by the Civil Protection Department in the event of a volcanic eruption and the evacuation plan for the red zone. Finally, we will review the latest statements released by the INGV (National Institute of Geophysics and Volcanology) following the most recent earthquake.
Table of Contents
- What Are the Phlegraean Fields and Why Are They Called That?
- Where Are the Phlegraean Fields Located?
- When Did the Last Eruption of the Phlegraean Fields Occur?
- Are the Phlegraean Fields and Vesuvius Connected?
- Which Volcanoes Are Part of the Campanian Volcanic System?
- Ongoing Seismicity in the Phlegraean Fields and Major Seismic Events
- Ground Uplift in the Phlegraean Fields
- Civil Protection Measures in the Event of an Eruption
- The Red Zone and the Evacuation Plan
- Statements from INGV After the Magnitude 4.2 Earthquake
What Are the Phlegraean Fields and Why Are They Called That?
The Phlegraean Fields are a vast volcanic area located in the metropolitan area of Naples, in the Campania region.
Their name derives from the Greek “Phlegrai,” meaning “burning” or “fiery,” due to the presence of numerous geothermal phenomena, including hot springs and fumaroles.
This region is known for its volcanic and geothermal activity, and it is characterized by terrain that shows clear signs of uplift and subsidence.
Where Are the Phlegraean Fields Located?
The Phlegraean Fields extend mainly beneath the city of Pozzuoli and some surrounding areas. The volcanic area, which also stretches underwater into the Gulf of Pozzuoli, is characterized by numerous volcanic cones and craters produced by eruptions over the past 60,000 years.
During this period, the area has experienced hundreds of eruptions, some of which were very large and destructive, such as the Campanian Ignimbrite eruption (approximately 39,000 years ago) and the Neapolitan Yellow Tuff eruption (about 15,000 years ago), which respectively produced around 200 km³ and 50 km³ of magma in a single event.
These massive eruptions caused the ground to collapse, forming a sub-circular depression known as a caldera.
When Did the Last Eruption of the Phlegraean Fields Occur?
The most recent eruption in historical times occurred in 1538 (the Monte Nuovo eruption), a few kilometers west of Pozzuoli. The event buried the village of Tripergole and caused significant damage to the city of Pozzuoli.
Are the Phlegraean Fields and Vesuvius Connected?
A frequently asked question is whether the Phlegraean Fields and Mount Vesuvius are connected.
Yes, the Phlegraean Fields and Vesuvius are geologically and volcanically connected. Both belong to the Campanian Volcanic System, a vast volcanic region in Campania, Italy. This system is known for its volcanic and geothermal activity and is considered one of the most complex in the world.
The two volcanoes share a common volcanic history and similar geological origins. Both have experienced past and present volcanic activity that has significantly shaped the geography and history of the region.
However, although they share geological connections, the Phlegraean Fields and Vesuvius are distinct and separate entities. Both represent potential volcanic hazards for the densely populated metropolitan area of Naples and surrounding communities, which is why they are closely monitored by authorities and experts.
Which Volcanoes Are Part of the Campanian Volcanic System?
The Campanian Volcanic System includes several volcanoes, the most notable being:
Mount Vesuvius
One of the most famous volcanoes in the world, known for the devastating eruption of AD 79 that buried Pompeii and Herculaneum. Located near Naples, it remains active, with its last significant eruption occurring in 1944.
Phlegraean Fields (Campi Flegrei)
A vast volcanic caldera in the western area of Naples, home to many craters, thermal springs, and geothermal activity. It is known for both past and ongoing volcanic unrest, including the current seismic swarm.
Ischia
The island of Ischia in the Gulf of Naples is of volcanic origin, characterized by thermal springs and geothermal phenomena. Its best-known volcanic structure is Mount Epomeo.
Together with smaller volcanic centers and geothermal activity, these features form the complex Campanian Volcanic System—one of Italy’s highest-risk volcanic areas.
Ongoing Seismicity in the Phlegraean Fields and Major Seismic Events
In recent days, the Phlegraean Fields have been affected by a seismic swarm that has produced several earthquakes, some of notable magnitude.
Among the most significant events was a magnitude 4.2 earthquake that occurred on September 27, 2023, at 3:35 AM, causing concern among local residents. The ongoing seismicity has been closely monitored by authorities and experts.
Ground Uplift in the Phlegraean Fields
According to the National Institute of Geophysics and Volcanology, ground deformation monitoring networks confirm a radial uplift pattern centered in the Pozzuoli area, with a maximum rate of approximately 15 ± 3 mm/month since January 2023.
The uplift recorded at the RITE GNSS station has reached about 113 cm since November 2005, including about 80 cm since January 2016.
Civil Protection Measures in the Event of an Eruption
In the event of a volcanic eruption in the Phlegraean Fields, the Civil Protection Department has established an evacuation and protection plan for the population.
This plan includes evacuation of high-risk areas, assistance for displaced residents, and emergency management. Local authorities work continuously to prepare communities for potential volcanic crises.
The Red Zone and the Evacuation Plan
The red zone is the area considered at highest risk in the event of an imminent volcanic eruption. Authorities define this zone based on scientific forecasts and the expected severity of the volcanic event.
Evacuation plans include transferring residents to designated safe areas and providing assistance.
According to the Civil Protection Department:
“Evacuation of the population from the red zone begins with the declaration of the ‘alarm’ phase. Areas of assembly designated by the municipal civil protection plans are shown in blue on the map—these are where citizens who choose assisted transport will gather. From the assembly areas, citizens will be taken to meeting areas (shown in green on the map) designated by the national civil protection plan. From there, they will reach the paired Regions or Autonomous Provinces by ship, train, or bus.”
Statements from INGV After the Magnitude 4.2 Earthquake
Following the magnitude 4.2 earthquake recorded in the Phlegraean Fields, the INGV released updated information on the seismic and volcanic situation.
Carlo Doglioni, president of the National Institute of Geophysics and Volcanology, stated before the Italian Chamber of Deputies:
“Our concern is linked both to the seismicity and to the fact that these temperatures in particular locations could trigger small phreatic explosions. These are not magma eruptions, but water in a supercritical state that can cause explosions.”
He added:
“Considering that seismic activity has been increasing in recent months, at the moment we do not see an end. It may end quickly, or the evolution could become even more disruptive.”
This post is also available in: Italiano (Italian)
