Earthquakes due to bradisism in Campi Flegrei has aroused concern in the past months not only among the population but also – and above all – at the level public/administrative. In this scenario, an intense area monitoring activities contributed to the formation of a important wealth of technical informationrelating to the identification of any latent erutive phenomena (for which so far There is no evidence on which there is consent of the scientific community).
However, as often happens, the recent retirement of the seismic activity has put in the background the critical issues present, despite the structural vulnerability of the existing built. In this perspective, the interest of local administrations has guided the development of scientific studies (reported among the references of this article) which give important quantifications of seismic risk and identify effects of future similar bradisismic activities: we summarize the salient points of the research here. How can you intervene to reduce seismic risk in this area?
The bradyseismic situation in the Flegrei fields to today, numbers in hand
The seismic activity of the Campi Flegrei is one of the manifestations of what is scientifically identified as bradisismic crisis. This, in fact, manifests itself as gods more or less long periods of the soil liftingwith annexes quite frequent earthquakesalthough – so far – of mild intensity. It is believed, even if it is not the only possibilitythat the movements of the soil originated from the pressures generated by the deep magma and the gases produced which, pushing, cause the lifting of the soil and consequent shocks.
In this case, the last bradisismic crisis, the one currently in progress, has led in the last period to important accelerations of the lifting movements, with Speed up to about 2 cm/month in 2024 and registering about 9000 earthquakesseveral condensate in the year 2022 (where peaks of 1000 earthquakes per month were also reached). The following image represents an excursus, also characterizing the importance of events in terms of magnitude.
Recent interdisciplinary studieswhich involve large groups of physicists, geologists, and engineerspublished in international scientific journals, including Nature Communicationsthe characteristics of the earthquakes related to bradisismic activity quantify with cutting -edge methodologies. The importance of these studies, in fact, is to be found above all in theapplication of innovative risk quantification methods with an updated database on seismic activities of the areawhich considers all the events recorded in one of the most monitored geographical areas in the world.
The numbers relating to the existing built of the Flegrei Campi
The recent numbers, deriving from national census, identify About 85000 inhabitants and 15000 buildings interested in the area subject to current important bradisismic movements. However, it is also to be considered the fact that the Flegrei camps are located in an area close to the municipality of Naples, which represents the third Italian city by population. The existing built of Pozzuoli, the largest inhabited center in the entire Phlegraean area, has almost the 90% of masonry buildings and reinforced concrete, less than 10% built after the 2000s. The result is a current photograph that is substantially not able to guarantee the same level of security of a construction made with recent anti -seismic design canons, established only in recent decades. Therefore, although not purely associated with an erupting danger, it has the same importance to quantify the actual degree of indirect seismic risk that undergoes the areaas well as what the gain may be if appropriate mitigation strategies of this risk were used.
The results of scientific studies on the Flegrei fields
By applying methodologies and analysis to the state of art, considering the presence of all recent seismic events followed following the recent bradisismic crisis, the studies discussed here report a detailed technical analysis on the potential structural effects related to the presence of new shocks. In detail, the scientific study reports important quantifications relating to the values of Magnitude momentlinked to seismic events that can be developed in calderathat is, in the deformation area. Specifically, it was evaluated that The magnitude potential in the area is in the interval 4.4-5.1with the latter scenario deemed unlikely by researchers.
From a structural point of view, it was evaluated that such magnitudemostly, they should not determine worrying stresses for constructions to the state of the art of regulations. It is clear that it is really difficult “exceed“The project values of seismic actions for new buildings with an event that develops in the caldera following events attributable to the phenomena related to the bradisismic crisis.
At the same time, since it cannot be completely excluded that earthquakes extend out of the caldera, in the case of particularly intense events, the chances of observing magnitude> 5 with probabilistic techniques advanced have been calculated. Studies show that this probability is strongly variable over time, but above all It is linked to the seismic activity observed in the short term.
The projection on existing buildings
Although the result that the earthquakes in the caldera The structures built according to current regulations should not crisis is comforting in general, the problem that the analysis faced refers to a constructive photography remains clear which is not real. As discussed before, the existing constructed is mainly composed of buildings that do not comply with current regulatory requirements: in a nutshell, they are designed with lower seismic actions than those with which it should currently be designed or in the absence of any seismic prescription. What does this entail? Simply, the magnitude of the time we discussed could still cause damage to the built assetsespecially in the epicentral area.
The quantification of this effect is expressed, in the research work presented, in terms of bankruptcy rates: represents a measuring metric of seismic risk and identifies (simplifying) the number of earthquakes that in one year would cause the bankruptcy of the construction. Calculations in hand, the projections show how structural interventions that sights to adapt buildings to current regulatory standards, would lead to one reduction of the risk of deathfor reinforced concrete buildings for example, More than 70%.
