After the new recent seismic events that have affected i Campi Flegrei In the past week, the problems related to the safety of buildings and the vulnerability of the existing constructed under the seismic actions induced by bradisism. A well -known problem e to the attention of the professionals for some timethanks to the coordination of the Department of Civil Protection and the scientific support of several local university university interdipartimental structures. The theme is of extreme relevance, given the Bradisismic crisis in progress in the area (where about 80,000 people live) and deserves an objective reflection that limits alarmism, but at the same time acts as a popular flywheel on the theme of seismic risk, feeding a healthy and personal awareness on the matter.
Stresses to buildings during the last seismic swarm
The update of the Vesuvian Observatory regarding the latest seismic events reports the registration of approx 672 earthquakeswith shocks followed from February 15th until February 20 and maximum recorded magnitude equal to 4.0. Although multiparametric monitoring confirms the absence of anomalies by all the parameters other than seismicity – keeping the usual increase trend (for example, soil lifting proceeds to an average of about 10 millimeters per month) – the general fear It is aggravated by two important seismic events, which, among other things, have recorded important accelerations around the epicenter: the shaking maps show in fact accelerations of peak on the ground with values of about 0.5 times the acceleration of gravity. This accelerations is an important fact because represents a measure of the stresses that buildings are subjects during these events.
Seismic vulnerability of the Flegrei Campi: the expected scenarios and the procedures put in the field
Recent scientific studies have evaluated that seismic events relating to the magnitude of interest, mostly, should not determine worrying stresses for buildings built according to current regulatory requirementsIn other words, it is really difficult to “exceed” the project values of seismic actions for new buildings. Nonetheless, the problem remains linked to existing buildings.
In this phase, the expected scenario is in common vision between the insiders: according to the current knowledge on the phenomenon and its evolution, given also the historical past, Nobody expects particular catastrophes from a structural point of viewto understand widespread or even localized, partial or global collapses of individual buildings. Nevertheless, for events with magnitude capable of producing similar shaking maps, or even just worse, to those first shown, damage, so -called non -structural, to build are expected. It means that the main elements of the construction are not involved in damage, but can occur Local or widespread breaks of buffering, crack more or less extensive in structures more ancient, cracks of plaster or Revertible of heavy shelves (As among other things, it has already happened in some past event). To confirm this, in the recent post-seismic post-event monitoring and inspection activities in Bagnoli, buildings close to the epicenter have shown the presence of damagealthough not very significant, A darkening walls.
To face in a targeted and objective way, the seismic effects on the existing constructed is underway Extraordinary plan for the analysis of the vulnerabilities of the areas directly affected by the bradisismic phenomenon (foreseen by Law Decree 140 of 2023). The creation of a Detailed structural vulnerability map: Currently, they are about 12,700 Make -up buildings “from the outside”, analyzed by specialized technicians with the 0bietive to trace a shipping and preliminary evaluation of their vulnerability. The recurring structural types, the materials used and constructive details, with particular identification of any anti-seismic precautions present were investigated and classified. Of the buildings registered, currently, among the residential ones, approximately 10% classified to high vulnerability.
The analysis conducted is currently preliminary and coarse, therefore requires greater technical reflections, possibly specialized building for building, after carrying out on the same in -depth investigations, also internal to the building. However, the same allows, in this phase and thanks to this preliminary screening, of identify the buildings on which to deepen the state of knowledgecategorize the interventions from the point of view of structural needs, quantify their costs and invasiveness. The analysis also allowed the identification of the areas with the highest concentration of vulnerable buildings. Through these results, it will therefore be possible to leave for plan interventions and assign any government funding for the mitigation of bradisismic risk.
