GNGTS 2024 - Atti del 42° Convegno Nazionale

Session 2.1 GNGTS 2024 The applications of seismic hazard assessments in civil society and the impact of its variations Mauro Dolce Interuniversity Consortium ReLUIS Whenever the results of seismic hazard analyses that enter into the decision-making processes of civil society (design, planning, etc.) have variations compared to previous ones, a great impact can be determined from different points of view. For example, due to the typical timing of the construction process of structures and infrastructures, new constructions or retrofitting interventions are designed for hazard values different from those of the models subsequently obtained and therefore, may be considered inadequate or excessively precautionary even before being built. This could imply a redesign and a further lengthening of construction times, or even retrofit immediately after their realisation. On the other hand, variations in hazard for models developed at different times can disorient people who are less experienced in probabilistic analysis of seismic hazard, causing a possible loss of confidence in the hazard assessments themselves. In order to encourage discussion and exchange of ideas, the proposed speech identifies and describes, without claiming to be exhaustive, the areas of application of seismic hazard assessments and the implications of variations in the officially adopted hazard models. In particular, the following areas will be considered: Ø Technical Standards for Construction (design of new buildings, safety assessment and risk classification of individual existing buildings, design of seismic retrofit Ø Seismic classification of territories (eligibility of areas for incentives aimed at the reduction of the risk of individual buildings or areas on which to carry out structural and non-structural prevention actions - microzonation/territorial planning) Ø Risk assessments at national and sub-national level (distribution of funds for seismic risk reduction, emergency planning) Ø Risk communication (risk awareness of citizens and local administrators) Ø Legal and judicial aspects (hindsight bias, according to which the varied hazard had to direct prevention interventions even before its official adoption) The non-negligibility of the impact of hazard variations requires that particular attention be paid to the management of the use, in the various fields, of the scientific models that may be developed, taking into account the current state of knowledge, the considerable uncertainties in the knowledge of the fundamental parameters and the divergences of approach in the scientific community.