Q&A
It is a volcanic structure consisting of a cauldron-like hollow formed by large explosive eruptions in the past. Therefore, it is morphologically different from the typical cone-shaped volcano. The caldera of the Phlegraean Fields stretches from Monte di Procida to Posillipo and includes an underwater area in the Gulf of Pozzuoli. It has been quiescent, that is, "dormant," since its last eruption in 1538, but it is still showing signs of activity such as seismicity, fumaroles, and ground deformation.
The term "bradyseism" comes from the Greek "bradýs," meaning "slow," and seismós, meaning "shake." It is a ground deformation involving slow lowering (subsidence) phases alternating with more rapid uplift phases. Rapid uplift can be followed by several earthquakes (earthquake swarms) that usually do not reach high magnitudes but are very shallow, easily perceived, and could sometimes damage buildings and infrastructure. The phenomenon is known to occur in the Phlegraean Fields and several volcanic calderas worldwide (e.g., Long Valley, USA; Rabaul, Papua New Guinea).
Unfortunately, it is impossible to predict the duration of this phenomenon.
Provided by the INGV Press Office and the "INGV Vulcani" Working Group
Currently, bradyseism results in ground uplift, triggered by a resurgence from the deep that results in the deformation and rise of the overlying rocks. During the deformation process, the rocks may reach a breaking point, resulting in an earthquake.
Provided by the INGV Press Office and the "INGV Vulcani" Working Group
During the subsidence phase at the end of the bradyseism crises in the 1970s and 1980s, the population did not notice any seismic activity. This led to the hypothesis that the crustal responses induced by stress during the uplift phase differ from those during the subsidence phase.
Provided by the INGV Press Office and the "INGV Vulcani" Working Group
Seismicity is the stress response induced by deformation processes. It is typically concentrated in areas where there is the greatest deformation, where the earth's crust shows weak points, or where the presence of fluids facilitating fracture is the highest.
Provided by the INGV Press Office and the "INGV Vulcani" Working Group
The Phlegraean Fields area experiences periods of ground uplift and subsidence. The area has been experiencing uplift since 2005, with the previous phase of bradyseism lasting about two years.
Provided by the INGV Press Office and the "INGV Vulcani" Working Group
According to Ingv's Vesuvius Observatory, which monitors the area with a multi-parameter network, no connection between the absence of gas at the Solfatara site and earthquakes has ever been shown.
The occurrence of earthquakes of higher magnitude and frequency may depend on the continuous accumulation of deformation-induced stress that has been loading the earth's crust for 19 years and on sudden increases in the uplift rate with more frequent fractures, which release more elastic energy.
Provided by the INGV Press Office and the "INGV Vulcani" Working Group
Considering both statistical analysis and historical seismicity in the area, the latest studies predict an expected maximum magnitude between 4.5 and 5.0 for bradyseism-related earthquakes.
Provided by the INGV Press Office and the "INGV Vulcani" Working Group
An earthquake is felt when the seismic waves it generates reach the surface of a populated area with enough energy to cause a tremor that people can feel. Even smaller seismic events located near a populated center can cause this shaking, not just strong earthquakes. Two buildings located close to each other can react differently to an earthquake due to differences in their construction type. Additionally, even if the buildings are close to each other, the soils and rocks on which they are built may have different properties.
Provided by the INGV Press Office and the "INGV Vulcani" Working Group
When you hear noises coming from the building structure during an earthquake, after making yourself safe, you should follow Civil Protection instructions and contact the appropriate municipal offices or the National Fire and Rescue Service.
Provided by the INGV Press Office and the "INGV Vulcani" Working Group
Potential evacuation of the population involves the "restricted intervention area" only if ground deformation and seismicity reach a level that could cause significant structural damage to buildings and infrastructure and if the situation becomes critical to the point where essential services for citizens can no longer be effectively guaranteed.
The perception of the smell of sulfur, which is frequent in some areas of the Phlegraean Fields, varies and depends on the direction of the wind, changes in atmospheric pressure, and possible variations in the rate of gas emission.
Provided by the INGV Press Office and the "INGV Vulcani" Working Group
The gases escaping from fumaroles are mainly water vapor, carbon dioxide, and small amounts of other gases.
Provided by the INGV Press Office and the "INGV Vulcani" Working Group
Dedicated studies of caldera activity indicate that long periods of unrest are often non-eruptive; that is, crises due to bradyseism do not often culminate in an eruption. This was the case in the 1970s and 1980s. However, sometimes unrest periods in calderas can precede an eruption.
According to probabilistic studies that rely on the eruptive history of the Phlegraean Fields, it is most likely that low-energy eruptions will occur, similar to the Monte Nuovo eruption of 1538. The likelihood of more powerful eruptions decreases progressively until Plinian-type events, which are considered unlikely but not with zero probability. However, the civil protection plan is designed for a medium-energy eruption.
Provided by the INGV Press Office and the "INGV Vulcani" Working Group
From 2012, prolonged changes were observed in specific geophysical and geochemical parameters monitored by the networks of the INGV—Vesuvius Observatory (increased seismic activity, alterations in the geochemical composition of fumaroles and gases, and ground uplift). As a result, the alert level was raised to yellow, and the operational phase of "attention" was activated.
Unrest is often used in volcanology to indicate when a volcano is active but dormant, that is, not involved in eruptive activity. Typical examples are increased seismic activity, ground deformation, or variations in the amount and type of gases emitted. The unrest phase may peak with the resumption of eruptive activity or end without consequences, with a progressive decrease in recorded signals. The length of this phase can vary widely, from a few days to decades. Volcanoes that enter a phase of unrest are subject to close surveillance.
Provided by the INGV Press Office and the "INGV Vulcani" Working Group
The red zone is an area at high risk for pyroclastic flows, which are extremely dangerous due to their high temperatures and speed. In this zone, in case of "alarm," preventive evacuation is the only protective measure for the population. The red zone includes the municipalities of Pozzuoli, Bacoli, Monte di Procida and Quarto; part of the municipalities of Giugliano in Campania and Marano di Napoli; some of the districts of Naples: Soccavo, Pianura, Bagnoli, Fuorigrotta and part of the districts of San Ferdinando, Posillipo, Chiaia, Arenella, Vomero, Chiaiano and Montecalvario. Within the area, there are approximately 500,000 residents.
The yellow zone is the area exposed to significant volcanic ash fallout in case of eruption. This area may require temporary evacuations of the population living in vulnerable buildings or those challenging to reach due to ash accumulation. The yellow zone includes the municipalities of Villaricca, Calvizzano, Marano di Napoli, Mugnano di Napoli, Melito di Napoli, and Casavatore and 24 districts of the City of Naples: Arenella, Avvocata, Barra, Chiaia, Chiaiano, Mercato, Miano, Montecalvario, Pendino, Piscinola, Poggioreale, Porto, San Carlo all'Arena, San Ferdinando, San Giovanni a Teduccio, San Giuseppe, San Lorenzo, San Pietro a Patierno, Scampia, Secondigliano, Stella, Vicaria, Vomero, and Zona Industriale. In the area, there are over 800 thousand residents.
Evacuation would affect only municipalities in the red zone, as defined by the National Emergency Planning for Volcanic Risk in the Phlegraean Fields.
View map
Evacuating citizens living in the red zone to other regions is essential to ensure access to healthcare, education, basic services, and accommodation. Small inland areas lack the necessary public infrastructure to support and sustain a significant population increase, for instance, accommodating the 80,000 residents of Pozzuoli. The population living in the red and yellow zones for volcanic risk constitutes around 50% of Campania's population. Relocating them to Campania would impact living conditions and organizational aspects, making it difficult to manage. However, anyone with alternative accommodation options in the region outside the red zone can always opt for autonomous accommodation.
The yellow zone is defined according to the probability of ash fallout and its accumulations that could cause damage. This probability depends on the direction of the wind at the time of the eruption. Meteorological studies have shown that winds in the Naples area typically blow in an east-southeast direction throughout the year. Therefore, the areas downwind from the caldera are at the highest risk of being affected by ash fallout.
Provided by the INGV Press Office and the "INGV Vulcani" Working Group
On the ING-Vesuvius Observatory and this website, you can find all the information about the state of activity and alert levels of the Phlegraean Fields. In addition, all the indications for actions and behaviors to be taken are available on the "I don't take risks" website. Besides, it is good to always check the web pages of your municipality of residence.
Provided by the INGV Press Office and the "INGV Vulcani" Working Group
Phlegraean Fields, Ischia, and Vesuvius belong to the same volcanic area and feature volcanoes characterized by somewhat similar magmas. At the level of shallow magmatic reservoirs, the three volcanoes are separate from each other and evolve independently. However, they belong to the same volcanic area and are probably related to a common geodynamic environment, which allowed the formation of magmas with similar properties.
Provided by the INGV Press Office and the "INGV Vulcani" Working Group
The Extraordinary plan for vulnerability analysis of built-up areas is foreseen by Art. 2 of Decree-Law 140/2023. The Plan provides for a series of urgent measures aimed at coping with the effects of the evolution of bradyseism, including through the use of simplified procedures. Such measures are:
- a seismic microzonation study;
- an analysis of the seismic vulnerability of private buildings aimed at identifying adequate mitigation measures and estimating the related financial requirements;
- an analysis of the seismic vulnerability of public buildings and, as a result, the development of an initial plan of measures for their mitigation;
- an implementation program for seismic and facility monitoring.
These measures refer to the intervention area, which includes part of the municipalities of Bacoli, Naples, and Pozzuoli most affected by bradyseism. View the map of the intervention area.
The Extraordinary plan for vulnerability analysis of built-up areas in relation to private buildings provides for an initial assessment of ordinary buildings (mainly for residential use and services) located in the " intervention area," i.e., in the areas of the municipalities of Pozzuoli, Naples, and Bacoli most affected by bradyseism. The aim is to improve knowledge of the built-up area and identify areas for further investigation.
In areas where buildings are found to be most vulnerable after an initial assessment conducted only from the outside, citizens can request a further inspection of their buildings.
Citizens living in the areas where the vulnerability analysis for private buildings is carried out can contact their municipality for specific questions. Please contact the Campania Region or the Department of Civil Protection for general information.
The intervention area is the area in which activities under the Extraordinary plan for vulnerability analysis are implemented, i.e., the area in the municipalities of Pozzuoli, Naples, and Bacoli most affected by bradyseism, thus ground deformation and seismicity. Please see the map available here to find out which territories are included in the intervention area.
Yes, residential buildings owned by ATER Agency (Agenzia Campana per l'Edilizia Residenziale) will be subject to vulnerability assessment under the Extraordinary plan for vulnerability analysis of ordinary private buildings.
The teams of technicians in charge of assessing private buildings, coordinated by the Civil Protection Department in conjunction with Campania Region and with the support of municipalities in the area, are equipped with identification badges. In the first phase of building assessment, they will not need to enter single buildings but will carry out the inspections from the outside.
An Extraordinary plan for vulnerability analysis of built-up areas has been drafted (art.2 of DL 140/2023) to investigate the state of the buildings in the areas of Naples, Pozzuoli, and Bacoli most affected by bradyseism, i.e., seismicity and ground deformation. The foresees an initial assessment of buildings from the outside, considering factors such as the construction period, materials used, number of floors, and state of preservation. Based on this assessment, a summary map will be created to identify the most vulnerable areas. Citizens will be allowed to request an additional investigation of their building free of charge. The ultimate objective is determining the total financial requirements for seismic upgrading of the most vulnerable buildings.
No such declaration will be provided during this stage or any subsequent stages. The inspections aim to assess the buildings' vulnerability and quantify the overall financial requirements for their possible seismic upgrading.
Currently, no funds have been allocated to upgrade private residential buildings. The building vulnerability analysis aims to evaluate possible seismic upgrading interventions and quantify their financial requirements.
At the end of the first phase of inspections, which should be completed between the end of June and the beginning of July 2024, a summary map will highlight the most vulnerable areas. At a later stage, citizens will be allowed to request an additional investigation of their building free of charge.
After the first assessment phase is completed, citizens whose homes are located in the most vulnerable areas of the intervention area will receive instructions on how to request an in-depth inspection from the municipality.
The purpose of conducting a seismic vulnerability analysis of private buildings under the Extraordinary plan is to provide citizens with a free assessment of the safety of their homes in light of the current bradyseism crisis. Analyzing private buildings will make it possible to quantify the overall financial requirements for seismic upgrading of the most vulnerable structures in the intervention area. However, it is currently uncertain if and what measures the state will take following the assessments.