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A multi-proxy record was acquired from a Late Pleistocene lacustrine succession in the Sulmona basin, central Italy. Previous and new tephrostratigraphic analyses of six volcanic ash layers constrain the investigated interval to between 92.3 and 115.0 ka. The δ18O composition is interpreted as a proxy for precipitation amount in the high-altitude catchment of the karst recharge system. The oxygen record shows millennial variability that is consistent with Greenland Interstadials GI25–23 and North Atlantic cold events C24–C22, indicating a strong Mediterranean–North Atlantic climate teleconnection. However, while no appreciable isotopic difference between the three interstadials is revealed by the Greenland record, the Sulmona section reveals a wetter climate during GI24 compared with GI23 and GI25. Comparison of our record with speleothem and pollen data from central and southern Italy suggests higher seasonality of the precipitation (wet winter–dry summer) for GI24, which matches a precession minimum. The wettest period recorded at Sulmona is also coincident with the deposition of Sapropel S4 in the Tyrrhenian Sea, suggesting a teleconnection between a higher seasonality in the western Mediterranean and strengthening of the boreal monsoon system.

The Calabrian Arc is the epicentral region of one third of the strongest earthquakes of Italy (Mw>=7.0). These are confined within a narrow peninsula which is the emerging portion of a slab-related accretionary wedge, and all occurred in the past four centuries. Therefore, here more than anywhere in Italy, historical seismicity alone is not sufficient for seismic hazard assessment. We carried out geological and paleoseismological studies in southern Calabria that allowed characterizing the seismogenic behavior of the Cittanova fault which was responsible for one of the most catastrophic earthquakes to ever occur in Europe, the Mw 7.0 5 February 1783 event. We have found out conclusive evidence for four Holocene earthquakes prior to 1783, with a recurrence time longer (~3.2kyr) than the other Apennine faults (0.3-2.4kyr). We have also estimated a robust slip rate for the late Upper Pleistocene (0.6mm/yr) and an extension rate (0.4mm/yr) that could reflect the residual back-arc opening of the Tyrrhenian Basin. Key Points Cittanova fault caused five Mw 7.0 earthquakes in the past 13 kyr Return times (~3.2 kyr) match low slip rate of the fault (0.6 mm/yr) Fault extension reflects residual Tyrrhenian back-arc opening.

This work is part of a broader project that aims to define a methodology for assessing the local seismic response on a large scale through a series of cognitive phases. Here we present the first phase that illustrates a procedure for the creation of standardised geothematic maps, at a national, regional and sub-regional scale, showing the geological and engineering-geological features that potentially induce stratigraphic amplification of the ground seismic motion. The main goal is to create a national reference legend to adopt, at different scales and detail, for complete coverage of the national territory. The method consists of consecutive steps that can be followed to obtain more detailed documents, starting from national scale geological maps, taking into account all the possible geological contexts characterising the Italian Peninsula. The first step is the reclassification of the lithostratigraphic units from the most detailed, reliable and updated available geological maps, in order to compose homogeneous geological and engineering geological maps at national scale. The construction of the legend and the elements contained in it plays a fundamental role in the process and constitutes the reference for more detailed maps at larger scales. We consider the age and the genetic domain to identify 10 main geological categories and from these, considering the prevailing lithological characters, to distinguish 27 geological groups. The engineeringgeological map at national scale derives from the combination of the geological groups with the engineeringgeological groups, representing the main characters of the cover terrains on the base of the main grain size and the geological substratum categories, adopted in the seismic microzonation studies (Technical Commission for Seismic Microzonation, 2020). At regional and sub-regional scale, we reclassified a more detailed geological map to convert it in an engineering-geological map of territorial context, characterised by the engineering-geological units adopted in the seismic microzonation studies of Italy. In order to reconstruct all the possible stratigraphic columns in term of the engineering-geological units in the territorial context representative of the shallower subsoil (< 50 m in depth), we proposed a representation in matrix form that combines the outcropping engineering-geological units with the units of the subsoil. Where seismic microzonation studies are not available, the multiscale engineering-geological maps could represent a useful tool for the seismic hazard assessment for the territorial planning at regional and sub-regional scale. Furthermore our results will be able to use the data of dynamic parameters (i.e., the shear wave velocity Vs) stored in DB-SM (National Seismic Microzonation Database, www.webms.it), in order to characterise the engineering-geological units of the reconstructed successions. Despite the different observation scales of the national SM project, the proposed methodology can provide rules for applying the SM standards with the aim of carrying out a "review" of the studies already completed and directing those in the implementation phases towards homogeneity. At international level this methodology could be taken as a reference for planning SM studies.

Seismic liquefaction assessment at different geographical scales provides hazard maps at increasing levels of resolution and reliability. According to the considered level, the areas prone to liquefaction are identified based on specific predisposing and triggering factors, including geological and geotechnical subsoil properties and local seismicity. The robustness of the definition of these areas is strongly correlated to the availability and spatial distribution of this information. Moreover, the data type and quality considerably influence the method of analysis and the degree of uncertainty of the results. This work proposes a methodological approach to define maps in terms of liquefaction susceptibility at two different geographical scales (i.e., regional and sub-regional scale). The Calabria region in Southern Italy was studied for the scope, characterised by a relatively high level of seismicity and liquefaction occurrences recorded during the numerous historical earthquakes. At the regional scale, the level of zonation represents a preliminary assessment of areas potentially susceptible to liquefaction. The considered predisposing factors and geospatial variables were implemented from approximately 5520 available surveys, using geostatistical tools to filter inconsistent data and quantify uncertainties. A quantitative assessment of the liquefaction predisposition was also proposed at a sub-regional scale in the identified areas prone to liquefaction. A new proposal of a Territorial Liquefaction Predisposing Index was carried out by quantifying the uncertainty due to the limited availability of data with geostatistical methods. This approach could provide helpful information for land management and emergency planning to characterise the territory for liquefaction instability and optimise resources allocation to reduce the level of uncertainty at higher levels of analysis.

We present the first evidence of surface rupture along the causative fault of the 14 January 1703 earthquake (Mw 6.9, Italian central Apennines). This event was sourced by the ~30 km-long, Norcia fault system, responsible for another catastrophic event in Roman times, besides several destructive earthquakes in the last millennium. A dozen paleoseismological excavations have already investigated the surface ruptures occurred during the Holocene along the Cascia-Mt Alvagnano segments, as well as along secondary splays close to the Medieval Norcia Walls. Remarkably, the master fault bounding the Norcia-Campi basins have never be proved to rupture at the surface. An antique limekiln that was improvidently set across the main fault scarp provides the amazing evidence of an abrupt offset in the 1703 earthquake, which likely occurred during a liming process of carbonate stones. Obviously, the limekiln became useless, and was progressively buried by slope debris. The amount of the offset and the kinematics indicators surveyed in the site allow the strengthening of our knowledge on the seismogenic potential of the Norcia fault system, on its geomorphic rule, and on its impact on the human activities.

The instability risk of underground cavities is issue of concern particularly for areas densely urbanized as the case of many historical centers in Italy. Among the possible causes of the cavity damages up to collapse, the proposed work considers a particular triggering factor that is the dynamic loading induced by an earthquake. Thus, the seismic vulnerability of shallow cavities in soft rock is addressed by proposing a methodology based on an extensive parametric two-dimensional finite element analysis. The proposed methodology is extended to a significant number of realistic cases, considering the effect of the variability of some predisposing and triggering factors on the cavity stability like roof thickness and cavity width, presence of overburden on the top of the rock layer, seismic signal intensity. The seismic vulnerability of the studied cases is assessed through the minimum Factor of Safety calculated during the whole length of the dynamic analysis. Finally, the results of the parametric study are rearranged into 'seismic stability charts for cavities in soft rock' proposed to be adopted as preliminary level of screening, to assess the seismic vulnerability of shallow underground cavities in soft rock. The results of screening enable to identify the critical zones that need a detailed analysis, in consideration of their possible interaction with above-ground structures, infrastructures and human activities.

One of the most important controlling parameters of the seismic site response in terms of earthquake ground motions modification is the shear wave velocity (Vs) profile of the subsoil, that generally increases with depth because of geological age, cementation and overburden stress. There exist, however, geological settings where the velocity profile is characterized by inversions, when a stiffer layer (exhibiting higher Vs) overlies a softer one (with a lower Vs). When referring to the Italian territory, these conditions are widespread and require specific seismic site response analyses, both for structures and infrastructures design and for land planning. The aim of the present work is to study the effect of Vs inversion on seismic site response in recurrent Italian geological domains for application in seismic microzonation studies, i.e., at the miunicipality scale. Firstly, the most common Italian geological domains characterized by inversion of Vs profiles are identified. Afterwards, one-dimensional subsoil columns representative of each identified geological domain are defined, based on Italian database of the seismic microzonation. In the end, based on the subsoil models defined at previous steps, numerical simulations of 1D site response are performed, in order to evaluate the influence of Vs inversion on ground shaking in terms of shear strain profiles and acceleration response spectra at the ground surface. To take into account the variability in the input parameters, stochastic 1D analyses are carried out via Monte Carlo method assuming assigned statistical distribution for Vs profiles and nonlinear variation curves of the normalized shear modulus and the damping ratio with the shear strain.

Evaluation of bedrock stiffness and thickness effect on ground motion modification represent a key-issue in the perspective of seismic risk reduction policy, since the maximum depth of site prospection generally does not extend down to the stiff bedrock location. Site conditions were identified from the Italian database of seismic microzonation studies. Simplified and realistic numerical models were adopted, i.e. extended down to the soft and stiff bedrock, respectively, in order to perform seismic site response analyses. Results indicate that simplified numerical model provides a quantification of the surface ground motion modification with an error generally equal to ±10% with respect to the realistic model. Hence, the evaluation of seismic performance of sites based on simplified numerical models represents a support tool for seismic risk management at large area.

An integrated subsoil model for seismic microzonation in the Central Archaeological Area of Rome is presented in this study. This model was created in the framework of a research project aimed at evaluating the geohazard level affecting Palatine hill, Roman Forum and Coliseum. A multidisciplinary survey was carried out mainly in 2010 including continuous-coring boreholes, in situ and laboratory geotechnical tests, MASW, Cross and Down-Hole tests, ambient noise measurements, Electrical Resistivity Tomographies, Ground Penetrating Radar surveys. The surveying methodologies adopted in the surveying campaign are also presented here. A three step procedure adopted for creating the integrated subsoil model of Palatine hill and surrounding areas is described in detail. This procedure first involves the construction of a geological model starting mainly from boreholes' data interpretation and correlation. Geological formations are here interpreted in terms of lithofacies following their sedimentological features and then characteri-zed by means of their main physical properties (i.e. grain size distribution, void ratio, unit weight, plasticity index) to define a scheme of lithotypes. The lithotypes represent the "framework" to be characteri-zed in terms of dynamical properties to produce the final inputs for 1D and 2D numerical modeling of ground motion amplification effects aimed at the construction of seismic microzonation maps.