Despite the global acceptance of Site Response Analysis (SRA), the Equivalent Linear (EQL) methodology remains the prevailing choice for both seismic microzonation studies and engineering design, often favored over the more rigorous Non-Linear (NL) approaches owing to its computational simplicity. The disparity in results between the two modeling methodologies has been shown to correlate with the Shear Strain Index (SSI), an innovative metric defined as the ratio of the Peak Ground Velocity of the input motion to the time-averaged shear-wave velocity in the top 30 m. While successfully employed in the North American context, the applicability of the SSI has yet to be assessed against the backdrop of Italian seismicity. This research details a preliminary application of the SSI utility across the Italian peninsula, conducted through a synergistic collaboration with the Institute of Environmental Geology and Geoengineering of the National Research Council. The investigation involved the selection of 120 representative Italian sites supported by extensive geotechnical data. EQL dynamic analyses were executed, incorporating a variety of input ground motions. The mobilized shear strains are correlated with SSI, establishing a distinct predictive relationship tailored to the Italian seismic environment. These findings constitute a pivotal step toward a technical framework for classifying Italian territory into seismic hazard groups. Critically, this will facilitate the robust identification of high-risk zones where the implementation of NL dynamic analyses should be mandated for a more accurate assessment.

This study presents an integrated synthesis of the sedimentological, stratigraphic, and compositional characteristics, as well as the tectono-sedimentary evolution, of the lower–middle Messinian deep-water turbidite successions of the Southern Laga Basin (SLB), representing the final depocenter of the Marnoso-arenacea foredeep in the central Apennines. The analysis is based on the integration of previous datasets with new stratigraphic-sedimentological surveys (more than 100 sections for a total thickness of ~20 km) and correlation panels, allowing the reconstruction of the depositional architecture of a 3000 m thick turbidite complex that represents the deep-water sedimentation of a high-rank composite depositional sequence named the Laga Depositional Sequence (LDS). The latter consists of five low-rank sequences (Laga 1a, b, c, d, and Laga 2), organized into lowstand, transgressive, and highstand systems tracts, that in turn are characterized by the presence of several turbidite systems organized in forestepping and backstepping stacking patterns. The turbidite architecture elements include channels, channel–lobe transition zones, and basin-floor lobes, whose distribution and geometry are primarily controlled by depositional gradient, variations in sediment supply, and tectonic activity. The results highlight that, in tectonically active margin settings such as Apennine foreland basins, stratigraphic cyclicity and turbidite sedimentation are predominantly controlled by allogenic factors, such as tectonic and climate. The analysis of sedimentation and subsidence rates indicates comparable values (≈0.9–1.5 mm yr-1), with systematic variations between channel and lobe zones and among different systems tracts, reflecting changes in sediment supply, subsidence, and paleobathymetry. Basin evolution shows a progressive reduction in water depth and a transition from confined to semi-confined conditions, ultimately leading to basin infilling. From a tectonic perspective, basin configuration and evolution are strongly controlled by the propagation of thrust systems, which generated a complex seafloor topography and influenced both stratigraphic organization and facies distribution. The result of this study is significant because it describes an example of an internally deformed wedge recording the transition from a foredeep to a wedge-top depozone. It also provides a high-resolution, basin-scale stratigraphic dataset, which is uncommon for complex turbidite systems and demonstrates that classical sequence stratigraphic models, largely based on eustatic controls, are insufficient along tectonically active margins. It also contributes to a better understanding of confined turbidite systems, which are inherently more complex and less predictable than those of continental passive margins.

Anthropogenic sinkholes are rapid localized depressions caused by collapse above man-made underground cavities and are a growing urban hazard, amplified by ageing utilities and intense rainfall. Effective risk management requires maps identifying where susceptibility is highest and where people and assets are exposed. Here, risk is expressed as a normalized screening-level index (0-1), not an annual probability; the hazard term (H) is a susceptibility proxy. Rome is underlain by a dense, partly abandoned network of excavated cavities (pozzolana quarries, catacombs, galleries) whose degradation, with sewer leakage and flash-flooding, has contributed to increasing sinkholes. From the ISPRA inventory, we selected 1834 occurrences (1960-2023); given heterogeneous sources, results are interpreted as inventory-conditioned susceptibility. Events were integrated with similar to 2800 mapped cavities and nine geological and anthropogenic predictors. Spatio-temporal analyses indicate post-2010 acceleration and clustering near cavities, sewer collectors, and flood-prone areas. An XGBoost workflow produced a high-resolution Sinkhole Susceptibility Map with District-based spatial cross-validation performance of ROC-AUC = 0.915 +/- 0.04. SHAP interpretation shows susceptibility is dominated by cavity density/proximity and sewer-network variables, with secondary contributions from flood-prone areas. To translate hazard into impact (R = H & times; V & times; E), susceptibility was combined with building vulnerability and resident population at census-tract scale. The two highest risk classes include 1521 tracts (similar to 23%), with more than 400,000 residents (similar to 34%), and about & euro;127 billion exposure, concentrated in Districts 1-2 and 5-7. The workflow supports screening-level prioritisation and is designed for local retraining and updates as new data become available.

The Central Cryptoporticus on Rome's Palatine Hill is a key underground monument of the Imperial period whose accessibility and long-term conservation are increasingly constrained by localised deformation, differential settlement, and cavity-related instability. Because these hazards are strongly conditioned by the nature and evolution of the foundation interface, we investigated how stratigraphy, mineralogy, and microstructure interact to control present-day vulnerability. Lithofacies logging from three boreholes (S1, S2, 1MS) and a trench site was integrated with portable X-ray fluorescence (pXRF), X-ray diffraction (XRD), petrography, and soil micromorphology on representative foundation units: pedogenised floodplain deposits of the Aurelia formation (AEL), variably altered and cemented volcaniclastic deposits of the Villa Senni formation (VSN), and underlying fluvial sand-silt deposits of the Fosso del Torrino formation (FTR). Results show that AEL is best interpreted as a structured, compound palaeosol shaped by polyphase wetting-drying and pedogenic redistribution. Alluvial clay coatings, vertic fabrics/slickensides, Fe-Mn redox features, and carbonate nodules produce a centimetrescale mosaic of contrasting porosity and hydraulic behaviour, implying strong sensitivity to moisture change and water routing. In VSN, two end-member petrofacies coexist: a friable, pedogenised ash-rich facies where vitricderived material is extensively transformed into clays and secondary phases, and a more coherent lithoid facies strengthened by zeolite and calcite cementation. Although cementation increases cohesion locally, hydrous secondary phases and alteration pathways create moisture-sensitive fabrics that can promote microcracking and softening where saturation persists. Across the foundation profile, rainwater infiltration, percolation, and capillary rise couple AEL and VSN, driving shrink-swell deformation, alteration and cement redistribution, and spatially patchy CaCO3 re-precipitation that is insufficient to offset ongoing weakening. Where these moisture-sensitive horizons intersect a dense network of anthropogenic voids, the likelihood of deformation and local collapse increases, making differential settlement and cavity-roof instability the dominant hazards for the monument. The findings support conservation priorities focused on surface- and groundwater control, targeted stabilisation of the most compressible or voided foundation sectors, and long-term hydro-geotechnical monitoring.

Purpose The traditional Italian approach to seismic risk management has focused more on post-disaster recovery than proactive urban prevention policies. This has resulted in significant costs and has profoundly affected local communities and urban functionality. This paper aims to contribute to the debate on seismic prevention strategies by introducing a new planning tool for early recovery − the Early Recovery System (ERS) − along with a methodology for assessing its impact on post-earthquake urban functionality. Design/methodology/approach In this study, the authors introduced the ERS, a prevention instrument designed to identify a proto-system of essential urban elements suitable for seismic retrofitting − such as emergency facilities, healthcare centers, schools, areas for temporary housing and road networks − that represent the minimum core to be preserved after an earthquake to reduce urban vulnerability and facilitate recovery to begin. By calculating 18 indicators over various time intervals and across different ERS configurations, the authors generated recovery curves that illustrate urban functionality loss and recovery trajectories. These curves enable us to assess and identify the optimal ERS configuration for effective prevention strategies. Findings Applying this methodology in a counterfactual case study of L’Aquila following the 2009 earthquake demonstrates that the proposed variables and resulting recovery curves realistically reflect L’Aquila’s actual recovery trajectory. These results support the potential for abstracting the methodology and applying it within a more complex framework for risk scenario simulation. Originality/value The ERS may represent a significant step forward in developing an urban prevention tool for early recovery, one that could assist decision-makers in planning interventions and setting priorities to enhance territorial safety and resilience in earthquake-prone regions.

This paper presents a comprehensive methodology for reconstructing seismic bedrock and investigating its role in areas where seismic (i.e. amplification) and co-seismic (i.e. liquefaction) effects are expected. Reconstructing seismic bedrock can be challenging, particularly in the presence of deep interfaces. To address this, a field campaign was conducted in 2021 in the municipality of Terre del Reno (Po Plain, Italy), an area characterised by deep and liquefiable deposits and significant damage after the 20 May 2012 Mw 6.1 earthquake and its aftershocks. The newly acquired geophysical dataset comprises 107 single station ambient vibration data points, revealing high-amplitude HVSR curves in the 0.2–1 Hz range. The shear-wave velocity (Vs) profile used for geophysical imaging of the subsoil model incorporated results from available passive and active multichannel seismic arrays, enabling calibration of seismo-stratigraphic models. Additionally, 1D seismo-stratigraphies subjected to 1D modelling supported a parametric analysis useful for investigating uncertainties related to liquefaction triggering. Various synthetic input motions were simulated using the DEEPSOIL code. These results confirmed that the assumed depth of seismic bedrock significantly influences outcomes.

The phenomenon of liquefaction is nowadays sufficiently understood in terms of phenomenology and predisposing conditions. However, a better assessment of liquefaction risk is necessary to mitigate its effects and guide land-use planning choices, particularly in the context of post-earthquake reconstruction.This evidence comes from some recent events (e.g., New Zealand, 2010-2011; Emilia-Romagna 2012; Palu, 2018), in which liquefaction induced effects were, in some instances, considerably more severe than expected. This is the case of Terre del Reno (Emilia-Romagna region, Italy) which experienced significant liquefaction phenomena during the 2012 Emilia-Romagna earthquake sequence, characterized by two main events: Mw 6.1 and 5.9. In this area sand eruptions, settlements, lateral spreading, and ground fractures were observed, resulting in extensive and irregularly distributed damage to structures and infrastructure.This study deals with the evaluation of liquefaction susceptibility and development of liquefaction hazard map in complex stratigraphic condition through an integrated method and multilevel approach. The study area is characterized by complex geologic conditions and abrupt slope changes, typical of riverbank-channel systems.The analysis of liquefaction potential was conducted using simplified semi-empirical methods. The safety factor against this phenomenon was estimated at different depths, relying on soil properties obtained from penetrometric tests and seismic input. In addition to the calculation of liquefaction potential, the study also addressed the phenomenon of lateral spreading due to liquefaction. To date, the delimitation and representation of area prone to lateral spreading is not yet ruled by guidelines for the mitigation of liquefaction risks. Therefore, this study employed an empirical methodology based on original criteria and procedures to establish the perimeter of such areas.The cross-analysis between the prediction of indicators of liquefaction potential and the evidence of damage found following the May 20, 2012 earthquake (Mw 6.1) showed a clear correlation between slope and damage frequency, suggesting the possibility of applying an empirical method to define the probability of lateral spreading occurrence.

The near field condition in seismic events is characterized by its immediate proximity to the seismic source, and is widely proven that ground motion near a causative fault (Near field) can differ significantly from typical ground motion observed at greater distances (far field).Features of near-fault ground motion are high vertical accelerations and the occurrence of high-amplitude, long-duration (2–5s) pulses observed in velocity–time and displacement–time histories aligned with the fault's normal direction. These features and the other effects linked to this condition are critical factors in causing potential damage to structures as the seismic motion in the near-field can subject structures to seismic demands that differ from the design criteria, primarily in terms of intensity and the nature of ground motion.As the seismic hazard quantifies the ground motion expected at a given site, understanding and predicting near-field effects are vital for seismic hazard assessment, structural design, and risk mitigation in the areas where near-field conditions occur.This study aims to investigate the near-field effects in seismic events by employing two-dimension numerical simulations carried out with FLAC 2D Finite Difference Code, to reproduce the features observed during a real earthquake occurred.The selected area is the Norcia plain, one of the intermountain basins widely present in Central Italy—a context of significant interest due to its association with high seismic hazard and high exposure in urban agglomerations. Several active seismic stations have recorded the last important seismic sequence (Central Italy 2017-2018) in particular the third and largest event on 30th October (6.5 Mw), whose epicenter was located close to Norcia (4 km). The validity of near-field conditions for this event has already been established by previous studies.Other scientific studies have been carried out in this direction in similar geological contexts with other software and the advancing here proposed is performing simulations using a non-horizontal interface geometry to apply the seismic input, with both horizontal and vertical components. The simulations consider a geological and tectonic model with few variables changing to provide a comprehensive understanding of how results may be affected by the knowledge of the geological and geotechnical setting, gained from basic studies.This study could have important implications to suggest an updating of the seismic code and the general approach in the seismic design of structures located in the near field domain, for a careful and reliable assessment of seismic risk.

The Campi Flegrei area, located in southern Italy, is characterized by complex geological stratigraphy and elevate seismic and volcanic risks, exacerbated by ongoing bradyseismic phenomena.This region, located in a densely populated context, poses significant challenges for seismic hazard assessment due to its geological complexity, frequent seismic activity and the vulnerability of infrastructuresThe recently recorded seismic swarms, including those of 2023, further highlight the need for accurate subsurface characterization to assess and mitigate seismic risks.In this context, a geophysical campaign is being conducted as part of a larger project aimed at advancing seismic microzonation and providing detailed data for risk mitigation strategies. This contribution focuses on the application of an integrated geophysical methodology for reconstructing a detailed subsurface model for local seismic response analysis at several sites of particular interest for civil protection purposes in the Campi Flegrei area.In this study, new geophysical data were acquired and then processed through integration with geological data. Geophysical surveys include both passive seismic measurements, carried out with single-station and array configurations, and active seismic testing using the Multichannel Analysis of Surface Waves (MASW) method. These passive and active seismic techniques yield information on shear-waves velocity profiles and subsurface heterogeneities.The ongoing analyses aim to explore the characteristics of the volcanic subsurface, contributing to a better understanding of its structural complexity. A strong emphasis is placed on integrating geophysical and geological data to improve the resolution and accuracy of the subsurface model.This work highlights the critical role of non-invasive geophysical methodologies, such as passive and active seismic methods, in urban and volcanic areas. These efforts support the strategic objectives of urban geophysics by promoting urban resilience and sustainability, while also providing actionable insights for prevention and urban planning in the Campi Flegrei area.By integrating advanced geophysical techniques, this research enhances the understanding of subsurface properties and their interaction with seismic phenomena, laying the foundation for effective risk mitigation and resilience-building measures in this highly complex and dynamic region.

This study presents a detailed 3D lithofacies model of the Upper Pleistocene-Holocene Tiber Depositional Sequence (TDS) within the alluvial plain of Rome, Italy, developed using an integrated approach. A deterministic framework was used to establish 1D lithofacies constraints, while geostatistical algorithms, particularly indicator kriging, were employed to reconstruct the stacking patterns and interfingering of lithofacies within systems tracts. This methodology allows for the realistic depiction of depositional trends and stratigraphic architecture while addressing challenges posed by limited data density in unsampled locations. The resulting 3D model demonstrates its ability to honour observed data while enabling meaningful extrapolation of subsurface features. The model captures key evolutionary trends and aligns with the conceptual 2D stratigraphic reconstruction developed in this study and the sequence-stratigraphic framework of the TDS derived from previous studies. Stratigraphic cross-sections and 2D correlation profiles extracted from the 3D model reveal the depositional architecture and constrain the thickness and extent of primary lithofacies associations. Key findings include the identification of braided and meandering channel-belt complexes associated with poorly and well-drained floodplain deposits. The lowstand systems tract (LST) is characterised by extensive braided channel belts with high width-to-thickness ratios, while the transgressive systems tract (TST) exhibits vertically stacked meandering channels associated with poorly drained floodplains. The highstand systems tract (HST) shows increased channel clustering and lateral expansion of meandering channel belts, associated with well-drained floodplain deposits displaying pedogenic features. The findings highlight the strengths and limitations of two-point geostatistical algorithms, with indicator kriging outperforming traditional methods like Truncated Gaussian Simulation and Sequential Indicator Simulation in maintaining geological coherence and lateral continuity. The 3D model enhances our understanding of the Tiber alluvial basin evolution and provides a robust framework for urban geological applications. It serves as a pivotal tool for managing subsoil resources, mitigating geohazards, and preserving cultural heritage in densely populated areas. This approach demonstrates the feasibility of applying efficient, scalable techniques to model sedimentary successions in similar urbanised alluvial settings worldwide.

This study investigates the variability and uncertainty of shear wave velocity (Vs) with depth, focusing on the standard deviation of the natural logarithm of Vs (6lnVs) using a dataset of nearly 15,000 profiles from the Italian seismic microzonation studies. Seismic microzone clusters (SM), defined by geological and geophysical homogeneity, and geographical clusters (GC), based on survey density, were compared to evaluate their effectiveness in characterizing 6lnVs variability. Spatial correlation analyses were performed to define high-quality SM clusters, ensuring strong internal geological and geophysical consistency with a maximum pairwise distance of 4.5 km between Vs profiles. Results demonstrate that SM clusters reduce 6lnVs uncertainty by 14 % within the first 30 m, 9 % from 30 to 50 m, and 4 % from 50 to 80 m compared to GC clusters, highlighting the value of geological and geophysical refinement. These results can support a more accurate randomization of Vs profiles with depth in local seismic response analyses using 1D simulation codes, improving the reliability of site-specific seismic hazard assessments. The findings are validated against literature uncertainty thresholds, confirming the robustness of the SM approach. By analyzing 1120 SM clusters, this study offers a comprehensive framework for propagating uncertainties in seismic response simulations and surpasses the limitations of localized case studies. The large dataset of Vs profiles, associated with SM clusters, is publicly available at https://doi.org/10.5 281/zenodo.11263471 (Mori et al., 2024).

The extensive evaluation of the impact of local seismo-stratigraphic configurations on seismic ground motion presents significant challenges due to the necessity of considering the combined effects of uncertainty and smallscale lateral variability of the relevant parameters. To effectively explore these sources of uncertainty, a new Python-based computer program is proposed for one-dimensional seismic site response simulations, adopting the equivalent linear viscoelastic approach in the frequency domain. With respect to existing software, the code introduces new pre- and post-processing features, which also meet the specific requirements of seismic microzonation studies. Within the code, the complete spectrum of uncertainties related to local seismo-stratigraphic configurations, including lithotype successions, layer thicknesses, and seismic and geotechnical properties for the considered lithotypes, is managed by considering user-defined constraints and statistical properties of the relevant parameters. Additionally, a batch approach is offered, enabling the application of the procedure to an unlimited number of different scenarios. To demonstrate the potentiality of the proposed code, a comprehensive set of 90,000 local seismic site response analyses was conducted, showing a clear correlation between the amplification factors, the mean shear wave velocity in the upper 30 m, the fundamental frequency of the deposit and the depth to the seismic bedrock.

Defining a reliable subsoil model is one of the most crucial points in the evaluation of the local seismic response, especially when the study area presents a complex geological setting. Performing a large number of investigations during and subsequently a seismic crisis (following a strong earthquake) is useful for collecting valuable data. By applying a multidisciplinary approach, these data can be used for constraining and test the model, as well as for directly evaluating the effects of strong earthquakes on the environment and the distribution of structural damages in heavily populated areas. In the present study, through a new multidisciplinary experimental-numerical approach, we investigated the role of local site conditions on the damage observed in the Central Business District (CBD) of Wellington (New Zealand) after the 2016 M7.8 Kaiko over bar ura event. Numerical 1D/2D site response analyses were carried out to explore the hypothesis of damage exacerbation due to basin effects. Our numerical models were then validated by comparing the corresponding numerical amplification functions with those derived from the application of the standard spectral ratio technique to a large accelerogram dataset. This dataset was obtained by GeoNet stations deployed in the study area, including those operative during the 2016 M7.8 Kaiko over bar ura event. Differences in ground motion for near- and far-field events were highlighted. Our results show that the site response in the Wellington CBD was controlled by complex 2D/3D valley effects (mainly edge effects), which were related to the local buried geomorphology. Overall, these findings suggest that the type and location of an earthquake influence the maximum distance at which 2D effects (generated at the basin edge) are still detectable. Comparing our dataset with those from other published studies would be useful for clarifying the factors leading to an exacerbation of the seismic response in alluvial basins. This study has also possible implications for seismic hazard mitigation in cities built on such basins. We conclude that robust numerical 2D models can provide and capture notable characteristics of the ground motion associated with basin effects. These characteristics are fundamental for understanding basin effects and should be considered when formulating building regulations.

The near field condition in seismic events is characterized by its immediate proximity to the seismic source, and is widely proven that ground motion near a causative fault (Near field) can differ significantly from typical ground motion observed at greater distances (far field). Features of near-fault ground motion are high vertical accelerations and the occurrence of high-amplitude, long-duration (2–5s) pulses observed in velocity–time and displacement–time histories aligned with the fault's normal direction. These features and the other effects linked to this condition are critical factors in causing potential damage to structures as the seismic motion in the near-field can subject structures to seismic demands that differ from the design criteria, primarily in terms of intensity and the nature of ground motion. As the seismic hazard quantifies the ground motion expected at a given site, understanding and predicting near-field effects are vital for seismic hazard assessment, structural design, and risk mitigation in the areas where near-field conditions occur. This study aims to investigate the near-field effects in seismic events by employing two-dimension numerical simulations carried out with FLAC 2D Finite Difference Code, to reproduce the features observed during a real earthquake occurred. The selected area is the Norcia plain, one of the intermountain basins widely present in Central Italy—a context of significant interest due to its association with high seismic hazard and high exposure in urban agglomerations. Several active seismic stations have recorded the last important seismic sequence (Central Italy 2017-2018) in particular the third and largest event on 30th October (6.5 Mw), whose epicenter was located close to Norcia (4 km). The validity of near-field conditions for this event has already been established by previous studies. Other scientific studies have been carried out in this direction in similar geological contexts with other software and the advancing here proposed is performing simulations using a non-horizontal interface geometry to apply the seismic input, with both horizontal and vertical components. The simulations consider a geological and tectonic model with few variables changing to provide a comprehensive understanding of how results may be affected by the knowledge of the geological and geotechnical setting, gained from basic studies. This study could have important implications to suggest an updating of the seismic code and the general approach in the seismic design of structures located in the near field domain, for a careful and reliable assessment of seismic risk.

The seismic stability assessment of anthropogenic cavities is a challenging issue for land and urban planning, particularly in areas of possible interaction with surface structures and infrastructures. The paper proposes a novel methodology for the preliminary assessment at urban scale of the safety level against roof collapse of underground cavities under seismic actions through seismic stability charts, SSCs. The SSCs are the result of extensive parametric two-dimensional FEM analyses focused on cavities excavated in soft rock, as it is frequent in many inhabited areas all over the world. The study is mainly oriented to the instability of shallow cavities, includingthe effects at the ground surface. The SSCs allow evaluation of stability conditions of a generic cavity through a factor of safety, calculated as the minimum ratio between the resistant and loading bending moment of the critical sections of the cavity roof during the whole earthquake duration. The method is applied to the case study of Sant'Agata de' Goti, a historical center in Southern Italy, rising on top of a volcanic tuff ridge.

Somma-Vesuvius, Campi Flegrei, and Ischia are three active volcanoes in the Neapolitan Area (Italy). In this work, we evaluated the combined tephra fallout hazard posed by the three volcanoes on a large-size ( 600 km × 700 km) and high-resolution ( 3 km) domain. In order to explore the effect of the intrinsic variability in eruption and wind conditions on tephra hazard we used a probabilistic approach (probabilistic volcanic hazard assessment, PVHA). For Somma-Vesuvius and Campi Flegrei, we grouped the possible eruptive size classes into small-, medium- and large-scale eruptions, while for Ischia we considered only the large-scale scenario, as it is the only one that can affect the mainland. We created a synthetic dataset of ground loads by performing 1500 tephra dispersion simulations for each eruption size class of each volcano (for a total of 10,500 simulations) using the numerical model Fall3D. For each simulation, we randomly sampled the eruptive parameters from suitable probability density functions and meteorological conditions from the ERA5 reanalysis dataset on the period 1990–2020. The hazard evaluation has been performed using a Bayesian Event Tree (BET) approach accounting for the results of the simulations, the variability in vent location and the mean annual rates of eruption for each volcano and eruption size class. In this way we obtained a set of hazard maps for Southern Italy showing the threshold tephra load that would be exceeded with selected mean annual rates within a 50-year exposure time. We found that greater tephra load thresholds are exceeded in the south–south-eastern regions.

In recent years, community resilience assessment has also become a central issue in earthquake risk mitigation. However, the application of resilience concepts is extremely complex. In the study of seismic risk, applications are highly multidisciplinary. Consequently, they are often incomplete or partial. Although new rigorous mathematical models have been developed, most applications are extremely complicated and susceptible to the input data and skill of the user. Even more so, applications to real large-scale contexts are much more complex than applications on a local scale or on single structures. New models and procedures are needed to apply resilience principles in the formulation of mitigation strategies at regional or sub-regional scales. In the present study, the impact of a highway on a set of communities is evaluated. The seismic resilience of communities is assessed by integrating the seismic performances of bridges and viaducts with those of the connected housing systems. The latter are estimated by modelling their physical damage with vulnerability curves for buildings. The main results are illustrated and discussed.

Abstract. This research uses a large dataset from the Italian Seismic Microzonation Database, containing nearly 15,000 measured shear wave velocity (Vs) profiles across Italy, to investigate the uncertainties in seismic risk assessment. This extensive collection allows a detailed study of the seismic properties of soil with unparalleled precision. Our focus is on evaluating Vs variations with depth within uniformly clustered areas, known as seismic microzones. These zones are carefully identified based on their spatial correlation and homogeneity in geological, geophysical, and geotechnical characteristics, which are critical for accurate prediction of seismic response. We contrast these results with clusters formed purely based on geographic survey density (here defined geographic clusters), thereby assessing the depth of our understanding of the subsurface geological and geophysical context. These results were further compared with those reported in the seismic code and literature. This study of depth-dependent Vs variations helps to refine our models of subsurface seismic behaviour. Our main discoveries show that: 1) uncertainties associated with seismic microzones (geological and geophysical clusters) are consistently lower than those identified in geographic clusters, particularly in the first 30 m of depth; 2) Vs profile variations show negligible increases in uncertainty within a certain range of correlation distances (up to about 4,500 m); 3) uncertainties for seismic microzones are lower than those previously reported in seismic codes and in the literature, indicating the effectiveness and precision of our methodological approach. The results of this study significantly improve local seismic response analysis and highlight the critical role of depth and spatial correlation in understanding seismic hazard. The dataset is available at https://doi.org/10.5281/zenodo.10885590 (Mori et al., 2024).

Italy is highly vulnerable to seismic hazards, with historical earthquakes causing substantial casualties and economic losses. Despite this, Italian seismic risk management has traditionally prioritized post-disaster recovery instead of effective urban prevention strategies.This approach carries significant costs, profoundly affecting territorial functionality and local communities through losses, service interruptions, population and business displacement, and socio-cultural imbalances. Therefore, the speed of recovery plays a critical role in determining whether communities choose to rebuild or relocate permanently. To accelerate post-earthquake recovery and enhance urban resilience, effective disaster risk reduction policies centered on urban prevention strategies to safeguard territorial safety effectively, are needed.In this work, we introduced the Early Recovery System (ERS) framework that identifies essential urban elements such as emergency functions, healthcare facilities, schools, road networks, areas for temporary housing, and interfering buildings with potential for seismic retrofitting. Through the calculation of 18 indicators over different time intervals and across three hypothetical scenarios, we generated recovery curves that illustrate urban functionality loss and recovery trajectories, to establish the optimal prevention strategy to be adopted. Evaluation of the ERS framework in the case study of L’Aquila post-2009 earthquake demonstrates its potential to mitigate long-term urban functional disruptions and facilitate faster recovery.ERS may represent a further step towards constructing an urban prevention instrument for early recovery, that could support decision-makers in planning interventions and setting priorities based on common goals of territorial safety in earthquake-prone regions.