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In a recent work, we evidenced some empirical discrepancies between the macroseismic intensity estimates in Italy in the last decade with respect to those made previously. A possible reason might be the progressive adoption by Italian researchers of the European Macroseismic Scale (EMS) in place of the Mercalli Cancani Sieberg (MCS) scale mostly used up to 2009. In theory, in modern settlements where reinforced concrete (RC) buildings are increasingly replacing those in masonry, EMS should overestimate MCS because the former accounts for the lower vulnerability of RC whereas the latter does not because RC buildings were not considered at all by the MCS scale since they were almost absent at the time (1912–1932) when it was compiled by Sieberg. However, such theoretical inference is contradicted by the empirical evidence that, on average, MCS intensities really estimated in Italy over the past decade slightly overestimate EMS and not vice versa as it should be. A possible explanation is that the EMS scale had not been well calibrated to reproduce the MCS, as its authors intended to do. Another possible reason for the discrepancies between the last decade and the previous ones might be that the MCS scale applied today is not the same as that defined by Sieberg at the beginning of the twentieth century. In order to better understand the possible causes of such discrepancies, we present here a formal comparison between the definitions of the different degrees of such macroseismic scales. After such analysis, we might argue that another possible reason for the observed discrepancy may come from the inaccurate assessment of building vulnerability when assessing the EMS intensity. [ABSTRACT FROM AUTHOR]

Current seismic structural design makes use of a ground motion intensity that has a certain probability of being exceeded at a site of interest in a time interval or, equivalently, exceedance return period. The design intensities with the same return period are often collected in the form of maps deriving from probabilistic seismic hazard analysis (PSHA) for each of the sites of interest. Probability theory underlying PSHA dictates that, in any time interval, design intensities are expected to be exceeded in a fraction of sites that depends on the return period the map refers to. In the case of Italy, three different nationwide PSHA studies can be currently considered of relevance. In the study, the estimated areal fraction of the Italian territory exposed to exceedance of the design intensity from 2008 to 2019 was quantified for the three hazard models, based on ShakeMap data for instrumental earthquakes. In addition, the same fraction was calculated considering a sparse catalog of inferred ShakeMap for historical earthquakes that occurred over almost 1000 years. It was found that, despite the apparent differences in the hazard models, the estimated fraction of territory exposed to exceedance is comparable for all the considered hazard maps. [ABSTRACT FROM AUTHOR]

This study aims at developing new macroseismic intensity attenuation models valid for Italy by exploiting the most updated macroseismic dataset and earthquakes catalogue, as well as the information obtained from a critical analysis of the most recent models in the literature. Several different attenuation models have been calibrated as a function of the moment magnitude (Mw) and epicentral distance from 16,260 intensity data points, that are related to 119 earthquakes occurred after 1900. According to trends and residuals analysis, the preferred calibrated intensity attenuation function is a Log-Linear model for epicentral distance (Repi in km) and a linear model for Mw as: I MCS = 1.81 - 2.61 L o g R - 0.0039 R + 1.42 M w with pseudo hypocentral distance R = R epi 2 + 9.87 2 ; the estimated standard deviation is σ = 0.75. Also noteworthy is another model for macroseismic intensity attenuation that proved to be as good as the best model and shows higher sensitivity to physical parameters, such as focal depth and magnitude, especially in the epicentral area. Performance of all calibrated models was also checked on an independent set of 15 post-1900 Italian earthquakes. One of the results of the present work is the opportunity to define earthquake scenarios (e.g. probabilistic seismic hazard maps) in terms of Macroseismic Intensity and its related standard deviation, avoiding the uncertainties due to the conversion of various ground shaking parameters into intensity values. [ABSTRACT FROM AUTHOR]

In earthquake-prone countries, transport network managers need to perform extensive seismic risk assessments coping with a considerable number of bridges characterised by an unsatisfying knowledge level and designed in the past without anti-seismic requirements. This study proposes a framework for efficient risk assessment of multi-span girder bridges considering knowledge-based uncertainties. The framework is intended to be applied to risk-informed prioritisation of bridge portfolios. It is based on subsequent modules that involve the input of knowledge data, the simulation of knowledge-based uncertainties, simplified seismic analysis, fragility and loss assessment. The seismic vulnerability of a given bridge is represented by loss ratio percentiles related to a given seismic intensity measure which can be used to quantify the expected annual losses and the corresponding variability due to the influence of knowledge-based uncertainty. A case-study section demonstrates the framework for the widespread category of simply supported girder-reinforced concrete bridges. It addresses issues such as the use of optimal intensity measures, the required number of model realisations and discrepancies with respect to accurate nonlinear time-history analysis. Finally, an illustrative example of the proposed framework for eight case-study bridges in Southern Italy demonstrates its applicability for seismic risk-informed prioritisation of critical bridges and for directing in-depth knowledge data collections where needed. [ABSTRACT FROM AUTHOR]

The determination of ground motion is crucial to plan the appropriate emergency activities, especially in areas characterised by an intense seismic history like the Italian peninsula. Ground motion assessment is generally based on the seismological parameters reported in the instrumental and parametric seismic catalogues. Therefore, the computation of shaking scenarios of historical earthquakes is very challenging, due to the poorly constrained variables (i.e., magnitudes, epicentral location, seismogenic sources), derived from the macroseismic intensity. In this study, we propose a novel approach to investigate the location and parametrization of the seismogenic sources of historical earthquakes and derive shaking scenarios. To this aim, the ground motion of two historical events, the Fabriano (1741, Mw = 6.1, Imax IX MCS) and Camerino (1799, Mw = 6.1, Imax IX–X MCS) earthquakes is simulated. In order to include the site response, a Vs,30 map of the Umbria and Marche regions is created from near-surface data. Different causative faults solutions are tested, finally discussing the ideal seismogenic source based on the residual analysis between observed and simulated macroseismic intensities. The resultant shaking scenarios of the two events are obtained by integrating observed intensities and simulations. [ABSTRACT FROM AUTHOR]

In this paper, we tackle the problem of the intensity attenuation at Ischia, a critical parameter in a high seismic risk area such as this volcanic island. Starting from the new revised catalogue of local earthquakes, we select a dataset of 118 macroseismic observations related to the four main historical events and analyse the characteristics of the intensity attenuation according to both the deterministic and probabilistic approaches, under the assumption of a point seismic source and isotropic decay (circular spreading). In the deterministic analysis, we derive the attenuation law through an empirical model fitting the average values of ΔI (the difference between epicentral intensity I0 and intensities observed at a site IS) versus the epicentral distances by the least-square method. In the probabilistic approach, the distribution of IS conditioned on the epicentre-site distance is given through a binomial-beta model for each class of I0. In the Bayesian framework, the model parameter p is considered as a random variable to which we assign a Beta probability distribution on the basis of our prior belief derived from investigations on the attenuation in Italy. The mode of the binomial distribution is taken as the intensity expected at that site (Iexp). The entire calculation procedure has been implemented in a python plugin for QGIS® software that, given location and I0 (or magnitude) of the earthquake to be simulated, generates a probabilistic seismic scenario according to the deterministic or probabilistic models of attenuation. This tool may be applied in seismic risk analyses at a local scale or in the seismic surveillance to produce real-time intensity shake-maps for this volcanic area. [ABSTRACT FROM AUTHOR]

The concept of macroseismic intensity arose with the purpose of measuring the strength of an earthquake by the effects it causes on buildings, people, and domestic furnishings. From this perspective, buildings can be considered seismic sensors that record the shaking. Early scales were conceived at a time when buildings were mainly in masonry and therefore they could be used as markers of the intensity in case of earthquakes. Indeed, since they were fairly homogeneous, their level of damage could be considered as an indicator of the shaking level. In recent decades, the evolution of construction techniques have made the MCS scale unsuitable for damage assessment of buildings of various resistance. To overcome this problem the EMS-98 scale was designed. Because the MCS scale is still used in Italy, even in the presence of many reinforced concrete buildings, the purpose of this work is to show that the EMS-98 is the most suitable tool for assessing intensity as it is more consistent with the built environment. Theoretical and real intensity assessments, by both MCS and EMS-98, have been determined and compared, showing that nowadays intensity is a function of the vulnerability. MCS and EMS-98 would be comparable only when the building stock is composed of very vulnerable edifices (generally class A). Finally, thanks to the similarity of the two scales for old and vulnerable buildings, EMS-98 appears fully adequate to investigate historical earthquakes and represents a powerful tool to ensure continuity among earthquakes of different epochs. [ABSTRACT FROM AUTHOR]

UnReinforced Masonry (URM) buildings constitute the majority of the Italian building stock and represent one of the most vulnerable construction typologies, as emerged during the seismic events occurred in the last decades. The objective of the present work is the proposal of a methodology for the seismic vulnerability and fragility assessment of different typologies of URM buildings. Through the statistical analysis of post-earthquake damage survey forms and of census data, the most prevalent structural typologies were identified in the Emilia Romagna region (Italy), leading to the definition of two reference masonry buildings, built at the beginning of the XX century and representative of the building stock of the study area. These buildings were modeled according to the equivalent frame method and their seismic performance was studied by means of nonlinear static analyses, considering uncertainties on the mechanical properties of masonry, on the intensity of the seismic action and on the displacement demand calculation method. Through the definition of Response Surfaces, analytical fragility curves relative to the investigated structural typologies were determined for the different damage states. [ABSTRACT FROM AUTHOR]

Historical seismic sequences with multiple mainshocks or strong foreshocks and aftershocks make it difficult to attribute the damage distribution to one earthquake rather than another. As a matter of fact, historical reports often describe the cumulative picture of effects, preventing a correct reconstruction of what happened during the different earthquakes. This paper proposes a review of the catastrophic seismic sequence that hit central Italy starting from January 1703. The sequence is currently quoted in some seismic catalogues with three mainshocks that occurred on 14 and 16 January and 2 February, with magnitudes ranging between 6.0 and 6.9. The aim of this paper is to reconsider the sequence on a chronological basis, trying to reconstruct the impact of each single event, taking into account the damage progression when assigning macroseismic intensity. Through this approach, the earthquakes already quoted in the catalogue are reassessed as faithfully as possible, with a richer framework of knowledge than in the past. [ABSTRACT FROM AUTHOR]

The importance of non-structural elements on the seismic performance of buildings is now widely recognized. A building cannot achieve a life-safety or continuous functionality performance after an earthquake if all its non-structural elements are damaged and/or out of function. Suspended non-structural elements, such as piping and mechanical services, play a crucial role in maintaining life-safety and functionality of a building after an earthquake. The importance of non-structural elements for the seismic performance of buildings have prompted the development of both force-based and displacement-based seismic design methodologies that can be applied to suspended non-structural elements. This paper focuses on appraising force-based and displacement-based seismic design methodologies available in Europe for suspended non-structural elements by comparing fragility functions for a case-study suspended piping trapeze restraint installation layout located in a mid-to-high seismic zone in Italy. The aim of this study is to determine if the seismic design methodologies available for suspended non-structural elements are capable of producing archetypes that achieve a life-safety performance objective for a design level earthquake (return period of 475 years) and maintain a reasonable performance, in terms of life-safety, for other earthquake intensity levels. Advantages and disadvantages of these methodologies are also highlighted. [ABSTRACT FROM AUTHOR]

The 2022 MS 6.9 (MW 6.6) Menyuan earthquake occurred in the northeastern Tibetan Plateau and was recorded by a large number of recently installed micro-electro-mechanical system (MEMS) stations within 100-km fault distance. By comparing the pre-event noises and earthquake signals in time domain and frequency domain, it is found that the records are feasible to be used to analyze ground motion parameters. These records provide a database for analyzing the main features of the ground motions recorded by MEMS stations, in terms of ground motion models (GMMs), near-field impulsive characteristics, and seismic intensities. The observed ground motion parameters are compared with the predicted values by Boore et al. (Earthq Spectra 30(3):1057–1085, 2014) GMM model, and it is found that the GMM model predicts higher shaking at the short and medium periods and lower shaking at the long periods. However, the shaking intensities at the short periods for Central Italy 2016 earthquake sequence are well predicted by the GMM model. The observed Chinese seismic intensity (CSI) by instruments is compared with modified Mercalli intensity (MMI) and surveyed macroseismic intensity (SMI), and it is found that CSI values are 0.73 intensity unit greater than MMI values and high SMI can be well predicted by CSI. Ground motions at three stations are classified as pulse-like based on the methodology by Baltzopoulos et al. (Bull Seismol Soc Am 110(4):1495–1505, 2020), and whether the pulses have been caused by forward directivity or fling step is discussed, and only one station may be directivity related and the other two are still inconclusive. Finally the earthquake damage of a high-speed railway bridge in the intensity IX area is presented. [ABSTRACT FROM AUTHOR]

SUMMARY: We derived new, reversible relationships between macroseismic intensity (I), expressed in either the European Macroseismic (EMS-98) or the Mercalli–Cancani–Sieberg (MCS) scales and peak ground acceleration (PGA), peak ground velocity (PGV) and the spectral acceleration (SA) at 0.3, 1.0 and 3.0 s [SA(0.3), SA(1.0) and SA(3.0)] for Italy. We adopted the orthogonal distance regression technique to fit a quadratic function. This research aims to improve ground motion and intensity estimates for earthquake hazard applications, and for the calculation of shakemaps in Italy. To this end, the recently published INGe data set was used (https://doi.org/10.13127/inge.2). The new relations are: where PGA and SAs are expressed in cm s−2 and PGV is expressed in cm s−1. Tests performed to assess the robustness and the accuracy of the results demonstrate that adoption of quadratic relationships for this regression problem is a suitable choice within the range of values of the available data set. Comparison with similar published regressions for Italy evidences that the proposed relations provide statistically significant improved fits to the data. The new relations are also tested by inserting them in the ShakeMap system of the Italian configuration evidencing a significant improvement when compared to those implemented. [ABSTRACT FROM AUTHOR]

• Comprehensive study on the Church of Ss. Annunziata in Paestum, Italy. • Utilization of extensive photogrammetric survey for accurate geometric modelling. • Dynamic characterization in Abaqus environment for material modelling and local failure mechanism assessment. • Analysis under varying seismic intensities to evaluate structural behaviour and vulnerability. • Insights aid informed decision-making for preservation and restoration efforts. This paper presents a comprehensive study on the Church of Ss. Annunziata in Paestum (Italy), focusing on its historical reconstruction, current condition analysis, and dynamic characterization. An extensive photogrammetric survey employing terrestrial and aerial photography was conducted to establish an accurate geometric model of the church. Subsequently, the model was set up into Abaqus ambiance for dynamic characterization, material modelling and assessment of potential local failure mechanisms through nonlinear dynamic analysis under varying seismic intensities. The research provides valuable insights into the structural behaviour of the church and its vulnerability to seismic events, aiding in informed decision-making for preservation and restoration efforts. [ABSTRACT FROM AUTHOR]

The evaluation of a bridge's structural damage state following a seismic event and the decision on whether or not to open it to traffic under the threat of aftershocks (ASs) can significantly benefit from information about the mainshock (MS) earthquake's intensity at the site, the bridge's structural response, and the resulting damage experienced by critical structural components. This paper illustrates a Bayesian network (BN)‐based probabilistic framework for updating the AS risk of bridges, allowing integration of such information to reduce the uncertainty in evaluating the risk of bridge failure. Specifically, a BN is developed for describing the probabilistic relationship among various random variables (e.g., earthquake‐induced ground‐motion intensity, bridge response parameters, seismic damage, etc.) involved in the seismic damage assessment. This configuration allows users to leverage data observations from seismic stations, structural health monitoring (SHM) sensors and visual inspections (VIs). The framework is applied to a hypothetical bridge in Central Italy exposed to earthquake sequences. The uncertainty reduction in the estimate of the AS damage risk is evaluated by utilising various sources of information. It is shown that the information from accelerometers and VIs can significantly impact bridge damage estimates, thus affecting decision‐making under the threat of future ASs. [ABSTRACT FROM AUTHOR]

Seismic hazard maps from probabilistic seismic hazard analysis or PSHA collect, at different sites, the values of the (site-specific) ground motion intensity measures of interest that, taken individually, have the same exceedance return period. For large-scale analyses, a widely used intensity measure is the macroseismic (MS) intensity, that provides an assessment of the earthquake effect based on the observed consequences in the hit area. Hazard maps can be developed in terms of MS intensity, and some examples exist in this respect. In the case of Italy, the last MS hazard map is based on the same seismic source model (known as MPS04) adopted to derive the design seismic actions of the current building code, a study dating more than ten years ago. It provides results in terms of countrywide Mercalli–Cancani–Sieberg (MCS) intensity level with 475 years return period. This short paper presents and discusses MCS probabilistic seismic hazard maps for Italy based on a recent grid-seismicity source model, herein named MPS19, synthetizing the large effort of a wide scientific community. The results, which are obtained by means of classical PSHA, are given in the form of maps referring to the 475 years return period, and also others of earthquake engineering interest. Moreover, it is discussed that the return period does not univocally identifies the MS intensity because, although MS is, by definition, a discrete random variable, it is modelled, in a given earthquake, by means of a normal distribution, that is, treated as continuous. Thus, the maps of the minimum return period causing the occurrence or exceedance of different MCS intensities are also provided. Finally, the comparison between the 475 years return period hazard map presented and the one which is currently the point of reference in Italy, that is, computed using MPS04, is briefly discussed. All the computed maps are made available to the reader as supplemental material. [ABSTRACT FROM AUTHOR]

The present study focuses on seismic damage to 36 masonry churches observed after the 2016 Central Italy earthquake. In the sample, recurrent architectural and structural features were identified and accurately described. In order to classify the churches in the sample based on their safety level, their seismic vulnerability was assessed by adopting the simplified procedure proposed in the current Italian standards for cultural heritage. The observed damage, directly detected by the authors during the post-earthquake surveys, is presented and carefully described, highlighting the evolution of the damage. An analysis of the damage suffered by the inspected churches highlighted the most frequent causal mechanisms and the most vulnerable macroelements. Particular attention was devoted to computation of a damage index based on the observed damage as well as on the macroelements present in the surveyed churches. Moreover, a judgment of usability, i.e., whether a church could be occupied after a seismic event, was made using the official survey form and related to both the seismic intensity experienced and the observed damage index. An analysis of the collected data enabled consideration of the usability judgment with respect to the damage index values, computed according to the Italian standards. [ABSTRACT FROM AUTHOR]

The Italian historical earthquake record is among the richest worldwide; as such it allows the development of advanced techniques for retrieving quantitative information by calibration with recent earthquakes. Building on a pilot elaboration of northern Italy earthquakes, we developed a procedure for determining the focal depth of all Italian earthquakes from intensity data alone. In a second step the procedure calculates their magnitude, taking into account the inferred depth. Focal depth exhibits a substantial variability countrywide, but so far received little attention: pre-instrumental earthquakes were routinely "flattened" at upper crustal level (~10 km), on the grounds that the calculation of focal depth is heavily dependent on the largely unknown local propagation properties. We gathered a learning set of 42 earthquakes documented by reliable instrumental data and by numerous intensity observations. Rather unexpectedly we observe (1) that within 50 km from the epicenter the ground motion attenuation rate is primarily controlled by focal depth and largely independent of magnitude; (2) that within this distance the fluctuations of crustal attenuation properties are negligible countrywide; and (3) that knowing both the depth and the expected epicentral intensity makes it possible to estimate a reliable magnitude. [ABSTRACT FROM AUTHOR]

We investigate the differences in seismicity rate estimates from two historical earthquake catalogues obtained with two methodologies (Boxer and QUake-MD) calibrated on a common dataset of macroseismic intensities and calibration events. The two methodologies were then applied to a test data set of historical earthquakes covering the France, Italy and Switzerland Alpine region. Differences between the resulting magnitude estimates and instrumental magnitudes show a standard deviation of 0.4 for both methodologies, with a mean residual of 0.01 for Boxer and − 0.04 for Quake-MD. A systematic difference in magnitude estimates between the two methodologies that correlates with the depth estimated by Quake-MD has been observed. This is attributed to the difference in the treatment of the depth parameter between Boxer and QUake-MD. Nevertheless, differences in magnitude estimates between the two methodologies show a mean residual of 0.006 and a standard deviation of 0.35 resulting in seismicity rates that are not significantly different considering the associated uncertainties. Such results made us believe that the European community could gain in the reduction of epistemic uncertainties associated with the estimate of historical earthquake parameters by agreeing on a common macroseismic and calibration dataset across borders. These efforts should be strongly encouraged. On the other hand, we show that even in the ideal conditions of this benchmark (same calibration events and same macroseismic intensity dataset), methodological differences can lead to systematic differences in magnitude estimates. It is therefore paramount to explore different methodologies for a more realistic quantification of the epistemic uncertainties in estimates of maximum magnitudes and seismic activity rates. [ABSTRACT FROM AUTHOR]

A hybrid seismic fragility model for territorial-scale seismic vulnerability assessment of masonry buildings is developed and presented in this paper. The method combines expert-judgment and mechanical approaches to derive typological fragility curves for Italian residential masonry building stock. The first classifies Italian masonry buildings in five different typological classes as function of age of construction, structural typology, and seismic behaviour and damaging of buildings observed following the most severe earthquakes occurred in Italy. The second, based on numerical analyses results conducted on building prototypes, provides all the parameters necessary for developing fragility functions. Peak-Ground Acceleration (PGA) at Ultimate Limit State attainable by each building's class has been chosen as an Intensity Measure to represent fragility curves: three types of curve have been developed, each referred to mean, maximum and minimum value of PGAs defined for each building class. To represent the expected damage scenario for increasing earthquake intensities, a correlation between PGAs and Mercalli-Cancani-Sieber macroseismic intensity scale has been used and the corresponding fragility curves developed. Results show that the proposed building's classes are representative of the Italian masonry building stock and that fragility curves are effective for predicting both seismic vulnerability and expected damage scenarios for seismic-prone areas. Finally, the fragility curves have been compared with empirical curves obtained through a macroseismic approach on Italian masonry buildings available in literature, underlining the differences between the methods. [ABSTRACT FROM AUTHOR]

The geographic distribution of earthquake effects quantified in terms of macroseismic intensities, the so-called macroseismic field, provides basic information for several applications including source characterization of pre-instrumental earthquakes and risk analysis. Macroseismic fields of past earthquakes as inferred from historical documentation may present spatial gaps, due to the incompleteness of the available information. We present a probabilistic approach aimed at integrating incomplete intensity distributions by considering the Bayesian combination of estimates provided by intensity prediction equations (IPEs) and data documented at nearby localities, accounting for the relevant uncertainties and the discrete and ordinal nature of intensity values. The performance of the proposed methodology is tested at 28 Italian localities with long and rich seismic histories and for two well-known strong earthquakes (i.e., 1980 southern Italy and 2009 central Italy events). A possible application of the approach is also illustrated relative to a 16th-century earthquake in the northern Apennines. [ABSTRACT FROM AUTHOR]

This paper presents results from the dynamic monitoring of a reinforced concrete school building located in Camerino (central Italy) during the seismic swarm following the first main shock of the Central Italy earthquake that occurred in August 2016. After the main shock of August 24th, ambient vibration tests were executed on the building to identify its modal dynamic behavior, which was assumed as benchmark to study changes in the structural response because of the subsequent events. A three-day dynamic monitoring was then performed with the aim of investigating changes in the dynamic behavior of the building subjected to ambient and seismic excitations. A procedure to identify the nonlinear response of the structure subjected to seismic events is presented, starting from an optimization methodology that permits the identification of the structure dynamics within time windows in which the building dynamic behavior can be considered linear time-invariant. Data show the variability of the modal properties, resonance frequencies, and damping ratios of the building, with the earthquake intensity. [ABSTRACT FROM AUTHOR]

In the framework of seismic risk analyses at large scale, among the available methods for the vulnerability assessment the empirical and expert elicitation based ones still represent one of most widely used options. In fact, despite some drawbacks, they benefit of a direct correlation to the actual seismic behaviour of buildings and they are easy to handle also on huge stocks of buildings. Within this context, the paper illustrates a macroseismic vulnerability model for unreinforced masonry existing buildings that starts from the original proposal of Lagomarsino and Giovinazzi (Bull Earthquake Eng 4(4):445–463, 2006) and has further developed in recent years. The method may be classified as heuristic, in the sense that: (a) it is based on the expertise that is implicit in the European Macroseismic Scale (EMS98), with fuzzy assumptions on the binomial damage distribution; (b) it is calibrated on the observed damage in Italy, available in the database Da.D.O. developed by the Italian Department of Civil Protection (DPC). This approach guarantees a fairly well fitting with actual damage but, at the same time, ensures physically consistent results for both low and high values of the seismic intensity (for which observed data are incomplete or lacking). Moreover, the method provides a coherent distribution between the different damage levels. The valuable data in Da.D.O. allowed significant improvements of the method than its original version. The model has been recently applied in the context of ReLUIS project, funded by the DPC to support the development of Italian Risk Maps. To this aim, the vulnerability model has been applied for deriving fragility curves. This step requires to introduce a correlation law between the Macroseismic Intensity (adopted for the calibration of the model from a wide set of real damage data) and the Peak Ground Acceleration (at present, one of most used instrumental intensity measures); this conversion further increases the potential of the macroseismic method. As presented in the paper, the first applications of the model have produced plausible and consistent results at national scale, both in terms of damage scenarios and total risk (economic loss, consequences to people). [ABSTRACT FROM AUTHOR]

Macroseismic intensity provides a qualitative description of seismic damage. It can be associated with Ground Motion Parameters (GMPs), which are extracted in near real-time from instrumental recordings during an earthquake. Several formulations of this empirical association exist in literature for Italy, mainly focusing on the relationship between intensity expressed on the Mercalli-Cancani-Sieberg (MCS) scale and peak ground acceleration or velocity. They are usually in the form of Ground Motion to Intensity Conversion Equations (GMICEs), which treat intensity as a continuous quantity. We propose an alternative approach, the Gaussian Naïve Bayes (GNB) classifiers, which allows to correctly treat intensity according to its ordinal definition. As a comparison, we also implement a modified version of the standard GMICE approach. We expand the existing database of GMP/MCS-intensity points with new, high-quality accelerometric data recorded in Italy in the period from 2002 to 2016 and resample the database by treating the intermediate intensities with half integer values (which are not meaningful in the MCS description) as both belong to the above and below full integer classes with an assigned weight. As a result, we estimate a new set of regression relations and GNB probability distributions between integer MCS intensity classes and eight GMPs (peak acceleration, velocity, displacement, Arias and Housner intensities, spectral acceleration at 0.3, 1.0 and 3.0 s). Results based on PGA and PGV are the most stable on the whole intensity scale. GNB models score better than GMICEs in terms of performance on unseen data and classification scores. [ABSTRACT FROM AUTHOR]

The geographic distribution of earthquake effects quantified in terms of macroseismic intensities, the so-called macroseismic field, provides basic information for several scopes including source characterization of pre-instrumental earthquakes and risk analysis. Macroseismic fields of past earthquakes as inferred from historical documentation may present spatial gaps, due to the incompleteness of the available information. We present a probabilistic approach aimed at integrating incomplete intensity distributions by considering the Bayesian combination of estimates provided by Intensity Prediction Equations (IPEs) and data documented at nearby localities, accounting for the relevant uncertainties and the discrete and ordinal nature of intensity data. The performance of the proposed methodology is tested at 28 Italian localities with long and rich seismic histories, and for two well-known strong earthquakes (i.e., 1980 Southern Italy and 2009 Central Italy events). A possible application of the approach is also illustrated relative to a sixteenth century earthquake in Northern Apennines. [ABSTRACT FROM AUTHOR]

An application of the Complete Automatic Seismic Processor (CASP) for seismic monitoring is presented. Its integrated and iterative fully automatic procedure is able to achieve complete data analysis and significantly rapid elaborations. Its performance in real-time seismic monitoring and alerting is tested in the Trentino region (NE Italy) for the period 1st March 2018 – 31st August 2019. CASP precisely and accurately located 386 seismic events, with local magnitudes in the -0.8–3.4 range, and produced a seismic catalogue with a magnitude of completeness around 1.1. Automatic earthquake solutions, with average horizontal and vertical errors of 1.1 and 1.5 km, are very similar to those included in a manually revised reference catalogue. In addition, 146 detected events are located in the area of the local porphyry quarries. CASP alerts are delivered as Short Message Service (SMS), Telegram and e-mail messages within an average time of just over two minutes from the earthquake origin time. These alerts contain earthquake source parameters, ground shaking levels and instrumental intensities. CASP reliability, promptness and robustness permit to civil protection and decision makers to perform a monitoring primarily dedicated to emergency management, in order to evaluate both seismic sources and their effects (peak ground acceleration) at local targets, such as more inhabited territories and critical infrastructures (dams and hydropower plants). [ABSTRACT FROM AUTHOR]

On 24 August 2016 at 01:36 UTC a M L6.0 earthquake struck several villages in central Italy, among which Accumoli, Amatrice and Arquata del Tronto. The earthquake was recorded by about 350 seismic stations, causing 299 fatalities and damage with macroseismic intensities up to 11. The maximum acceleration was observed at Amatrice station (AMT) reaching 916 cm s–2 on E–W component, with epicentral distance of 15 km and Joyner and Boore distance to the fault surface (R JB) of less than a kilometre. Motivated by the high levels of observed ground motion and damage, we generate broad-band seismograms for engineering purposes by adopting a hybrid method. To infer the low frequency seismograms, we considered the kinematic slip model by Tinti et al. The high frequency seismograms were produced using a stochastic finite-fault model approach based on dynamic corner-frequency. Broad-band synthetic time-series were therefore obtained by merging the low and high frequency seismograms. Simulated hybrid ground motions were compared both with the observed ground motions and the ground-motion prediction equations (GMPEs), to explore their performance and to retrieve the region-specific parameters endorsed for the simulations. In the near-fault area we observed that hybrid simulations have a higher capability to detect near source effects and to reproduce the source complexity than the use of GMPEs. Indeed, the general good consistency found between synthetic and observed ground motion (both in the time and frequency domain), suggests that the use of regional-specific source scaling and attenuation parameters together with the source complexity in hybrid simulations improves ground motion estimations. To include the site effect in stochastic simulations at selected stations, we tested the use of amplification curves derived from HVRSs (horizontal-to-vertical response spectra) and from HVSRs (horizontal-to-vertical spectral ratios) rather than the use of generic curves according to NTC18 Italian seismic design code. We generally found a further reduction of residuals between observed and simulated both in terms of time histories and spectra. [ABSTRACT FROM AUTHOR]

A large amount of data about earthquake effects, supplied by citizens through a web-based questionnaire, enabled the analysis of the occurrence of many of the effects on humans and objects listed in macroseismic scales descriptions. Regarding the other diagnostic effects (rattling, moving, shifting, falling or overturning depending of the object type of doors, windows, china, glasses, small objects, pictures, vases, books, as well as frightened people and animal behaviour), data from more than 300,000 questionnaires about earthquakes felt in Italy from June 2007 to August 2017, were analysed by stacking them together as a function of hypocentral distance and magnitude. The comparison of the resulting percentages with the intensity prediction equation showed that almost all the chosen effects are good diagnostics for macroseismic intensity evaluation, as their percentages are well differentiated. We did not analyse the oscillations of hanging objects and liquids because the differences in effect attenuations, highlighted by the maps of the occurrence percentage, suggested to not consider them as diagnostic effect. This result allowed us to quantify the occurrence of each diagnostic effect for the intensity degrees from II to VI of the European macroseismic scale for the people who felt the earthquake. The application of the intensity assessment method to internet macroseismic data, based on the specifications herein proposed, should mitigate the problem of "not felt" undersampling in crowdsourced web data. [ABSTRACT FROM AUTHOR]

Summary: This study investigates the correlation properties of integral ground‐motion intensity measures (IMs) from Italian strong‐motion records. The considered integral IMs include 5–95% significant duration, Housner intensity, cumulative absolute velocity, and Arias intensity. Both IM spatial correlation and the correlation between different integral and amplitude‐based IMs (i.e., cross‐IM correlation) are addressed in this study. To this aim, a new Italian ground‐motion model (GMM) with spatial correlation for integral IMs is first introduced. Based on the newly developed GMM, the empirical correlation coefficients from interevent and intraevent residuals are investigated and various analytical correlation models between integral IMs and amplitude‐based IMs are proposed. The effective range parameter representing spatial correlation properties and the trend in the cross‐IM correlations are compared with existing models in the literature. The variability of the effective range parameters with respect to event‐specific features is also discussed. Modeling ground‐motion spatial and cross‐IM correlations is an important step in seismic hazard and risk assessment of spatially distributed systems. Investigating region‐specific correlation properties based on Italian strong‐motion records is of special interest as several correlation models have been developed based on global datasets, often lacking earthquakes in extensional regions such as Italy. [ABSTRACT FROM AUTHOR]

Past earthquakes have repeatedly shown that damage to masonry infills can produce large economic losses and even jeopardize human lives. Nevertheless, in current design practice masonry infills are ignored, while available macro-models for nonlinear analysis focus the attention on the In-Plane (IP) behavior of masonry infills only, while neglecting the Out-Of-Plane (OOP) collapse mechanism. The main objective of this study is to investigate the seismic performance of RC frame buildings accounting for the interaction between IP and OOP behavior of masonry infills. To this end, a suitable nonlinear model, able to capture the IP stiffness and strength reduction due to the OOP displacement demand (and vice versa) is implemented. The selected model incorporates a routine that removes infills from the structural model when either IP or OOP collapse occurs. Different building models, representative of typical residential buildings, realized in Italy (and other European countries) from 50's to 90's, are examined through nonlinear response-time history analysis at different earthquake intensity levels, with return period ranging from 30 to 5000 years. Two alternative infill configurations (single layer and double layer with inner cavity) are considered, in accordance with the construction practice of the time. The comparison between the models with and without IP/OOP interaction points out the relevance of the OOP behavior towards an accurate evaluation of the seismic performance of RC frame buildings. A set of fragility curves is tentatively proposed, for different building performance levels, ranging from immediate occupancy to life safety. [ABSTRACT FROM AUTHOR]

This study describes a deep convolutional neural network (CNN) based technique to predict intensity measurements (IMs) of earthquake ground shaking. The input data to the CNN model consists of multistation, 3C acceleration waveforms recorded during the 2016 Central Italy earthquake sequence for M  ≥ 3.0 events. Using a 10 s window starting at the earthquake origin time, we find that the CNN is capable of accurately predicting IMs at stations far from the epicentre which have not yet recorded the maximum ground shaking. The CNN IM predictions do not require previous knowledge of the earthquake source (location and magnitude). Comparison between the CNN model predictions and those obtained with the Bindi et al. GMPE (which requires location and magnitude) shows that the CNN model features similar error variance but smaller bias. Although the technique is not strictly designed for earthquake early warning, we find that it can provide useful estimates of ground motions within 15–20 s after earthquake origin time depending on various setup elements (e.g. times for data transmission, computation, latencies). The technique has been tested on raw data without any initial data pre-selection in order to closely replicate real-time data streaming. When noise examples were included with the earthquake data the CNN was found to be stable, accurately predicting the ground shaking intensity corresponding to the noise amplitude. [ABSTRACT FROM AUTHOR]

The parametric catalogue of Italian earthquakes CPTI15 (Catalogo Parametrico dei Terremoti Italiani) represents the latest of a 45-years-long tradition of earthquake catalogues for Italy, and a significant innovation with respect to its predecessors. CPTI15 combines all known information on significant Italian earthquakes of the period 1000–2017, balancing instrumental and macroseismic data. Although the compilation criteria are the same as in the previous CPTI11 version, released in 2012, the catalogue has been revised as concerns: the time coverage, extended to 2017; the associated macroseismic data, improved in quantity and quality; the considered instrumental data, new and/or updated; the energy thresholds, lowered to maximum or epicentral intensity 5 or magnitude 4.0 (instead of 5–6 and 4.5, respectively); the determination of parameters from macroseismic data, based on a new calibration; the instrumental magnitudes, resulting from new sets of data and new conversion relationships to Mw. The catalogue considers and harmonizes data of different types and origins, both macroseismic and instrumental. For all earthquakes, the magnitude is given in terms of true or proxy moment magnitude (Mw), with the related uncertainty. The compilation procedure rigorously implements data and methods published in peer-reviewed journals. All data and methods are clearly indicated in the catalogue, in order to guarantee the maximum transparency of the compilation procedures. As compared to previous CPTI releases, the final CPTI15 catalogue shows a frequency–magnitude distribution coherent with current Italian instrumental catalogues, making it suitable for statistical analysis of the time-space property of the Italian seismicity. [ABSTRACT FROM AUTHOR]

The densely populated Po Plain, a very deep sedimentary basin in northern Italy, is prone to heavy shaking during earthquakes. Seismic hazard assessment must account for local variation in wave amplification. Standard ground motion prediction equations may fail to picture the complexity of strong lateral gradients in seismic response, due to sharp structural heterogeneity. For this reason, there is an increasing demand for full waveform predictions for engineering applications. Here, we present an implementation of a hybrid broadband simulation based on the method of Mai et al. (Bull Seismol Soc Am 100(6):3338–3339, 2010), to obtain complete broadband seismograms of 0.1–10 Hz. With this method, low frequency (< 1 Hz) and high frequency (1–10 Hz) seismograms are simulated separately using a deterministic and a stochastic method, respectively. We apply the method to four events recorded within the Po basin, with magnitude ranging from Mw = 4.4 to Mw = 5.6. The low frequency (LF) simulation is performed using SPECFEM3D on a few test subsurface velocity models. The three-dimensional velocity model MAMBo (Molinari et al. in Bull Seismol Soc Am 105(2A):753–764, 2015)—consisting of a detailed structural description of the basin, based on extensive active-source data, embedded within a regional 3D crustal model—provided the best results for broadband simulations that most closely corresponded with the observations. It performed better than an ambient noise tomography model with more accurate S-wave velocities but less well defined layer topographies, emphasizing the importance of first order velocity discontinuities. The high frequency (HF) seismograms are simulated using the multiple scattering approach of Zeng et al. (J Geophys Res Solid Earth 96(B1):607–619, 1991). The scattering coefficients are obtained by performing a non linear inversion for each station to find best fitting synthetic envelopes. HF energy is then combined at ∼ 1 Hz to match the amplitude and phase spectra of the LF signal. We are able to simulate full waveforms throughout the Po Plain, of which shaking duration matches observed data for stations located in the basin. Shaking amplitudes are generally overestimated in the low frequency simulation by the MAMBo velocity model. Updating the MAMBo velocity model with more accurate S-wave velocity information of the ambient noise tomography model should improve the fit in future simulations. [ABSTRACT FROM AUTHOR]

SUMMARY In performance‐based seismic design, as adopted by several building codes worldwide, the structural performance is verified against ground motions that have predetermined exceedance return periods at the site of interest. Such a return period is evaluated by means of probabilistic seismic hazard analysis (PSHA), and the corresponding ground motion is often represented by the uniform hazard spectrum (UHS). The structural performance for ground motions larger than those considered in this design approach is, typically, not explicitly controlled under the assumption that they are sufficiently rare. On one hand, this does not achieve uniform safety at sites characterized by different design ground motions corresponding to the same return period; on the other hand, exceedances of the design spectra are systematically observed over large areas, for example in Italy. The latter issue is because of the nature of UHS, the exceedance of which is likely‐to‐almost‐certain when the construction site is in the epicentral area of moderate‐to‐high magnitude earthquakes (ie, the design spectrum may be not conservative at these locations), especially if PSHA is based on seismic source zones. The former is partially because of the systematic difference of ground motions for return periods larger than the design one at the different sites. Quantification of the expected ground motion given the exceedance of the design ground motions (ie, the recently introduced as the expected peak‐over‐threshold or POT) can be of help in quantitatively assessing these issues. In the study, a procedure to compute the POT distribution is derived first; second, POT spectra are introduced and used to help understanding why and how seismic structural reliability of code‐conforming structures decreases as the seismic hazard of the site increases; third, expected and 95th percentile POT maps are shown for Italy to discuss how much high hazard sites are exposed to much larger peak‐over‐threshold with respect to mid‐hazard and low‐hazard sites; finally the POT is discussed with respect to the slope of the hazard curve (in log‐log scale) at the threshold, a known proxy for ground motion beyond design. All data presented in the maps are made available for the interested reader as a supplemental archive. [ABSTRACT FROM AUTHOR]

Macroseismic intensity data are an important source to learn from historical earthquakes. Nevertheless, this data needs to be converted into more suitable intensity measures to be used in risk analyses, as well as in design practice. To this purpose, in this paper, correlations between macroseismic scales and ground motion parameters have been derived. Peak Ground Acceleration (PGA), Peak Ground Velocity (PGV) and Housner Intensity (IH) as instrumental measures, and European Macroseismic Scale (EMS-98) and Mercalli-Cancani-Sieberg (MCS) as macroseismic measures, have been considered. 179 ground-motion records belonging to 32 earthquake events occurred in Italy in the last 40 years have been selected, provided that for each record, macroseismic intensity in terms of either EMS-98 or MCS or both were also available. Statistical analyses have been carried out to derive both direct (i.e. macroseismic vs instrumental intensity) and inverse (instrumental vs macroseismic intensity) relationships. Results obtained from the proposed relationships have been analyzed and compared with some of the most prominent results available in the technical literature. [ABSTRACT FROM AUTHOR]

In Italy, earthquakes caused by volcanoes are of primary importance in the evaluation of seismic hazard, since several volcanoes seriously endanger densely populated areas (e.g. Catania and surroundings, Campi Flegrei, Vesuvius). On the other hand, there are very few models for the prediction of ground motion induced by volcanic events, mostly because observations are scarce and volcanic earthquakes less frequent than crustal events. Following the recent earthquakes in the Etna area (mainshock 26/12/2018 Mw = 4.9) and in the island of Ischia (mainshock 21/08/2017 Mw = 3.9), it was possible to increase the number of recordings for volcanic areas in Italy and, in particular, close to the epicentre. The data available after the recent events revealed the limitations of previous models and especially their inadequacy to predict the ground motion observed in the near source, that can be unexpectedly high. We calibrate a new empirical model to predict the amplitudes of several intensity measures for volcanic areas in Italy. The most relevant aspect in the proposed model is the different attenuation with the distance between shallow and deep events, with discerning focal depth fixed at 5 km. The equations are valid for the geometric mean of horizontal components of PGA, PGV and acceleration response spectra ordinates at 5% damping (in period range T = 0.025–5 s). The range of validity in magnitude is 3.5–4.9 and the hypocentral distance range is 1–200 km. [ABSTRACT FROM AUTHOR]

Since August 2016, Central Italy has been struck by three strong earthquakes (Mw 6.0 Amatrice, Mw 5.9 Visso and Mw 6.5 Norcia). This seismic sequence resulted in ground failure, infrastructural damages and destruction of several villages. This work aims to analyze the site effects on the ground shaking along the valley of the Tronto River across the Acquasanta Terme municipality, where some historical sites were located. These suffered heavy and differentiated damage during the seismic sequence. Following the Amatrice earthquake of August 24, authors managed the deployment and acquisition of seismic stations located in an array along the valley of the Tronto River approximately 25 km from the epicenter. By recording the two stronger earthquakes (i.e., Mw 5.9 Visso and Mw 6.5 Norcia) and 30 aftershocks with varying magnitudes and also ambient vibration, the site effects were preliminarily studied using the horizontal-to-vertical spectral ratio (HVSR). Furthermore, the amplification effects on the ground motion were also evaluated with reference to the earthquakes in terms of the standard spectral ratio (SSR) and the normalized energy content, in both cases using the bottom of the valley where the seismic bedrock outcrops as a reference. The comparison between the spectral accelerations due to the two strong earthquakes and those provided by ground motion prediction equations displayed values that were usually inadequately precautionary for periods lower than 0.35 s. High spectral accelerations were detected in period ranges corresponding to those predominant for masonry structures that are available in the literature. According to the current knowledge about surface geology, the local site effects seem to have significantly influenced ground shaking along the slopes of the valley, thus producing a larger seismic effect on ancient structures with more than two floors. The results can provide useful information for undertaking a possible future microzonation study that would be able to support urban planning and seismic designs in the rebuilding phase. [ABSTRACT FROM AUTHOR]

On 24th of August 2016 a strong earthquake (Ml 6.0; Mw 6.0) struck Central Italy, causing destruction and about 300 victims. The earthquake was the first in a long-lasting seismic sequence characterized by seven events of magnitude larger than 5.4, with the main event of Mw 6.5 occurring on 30th of October 2016. A macroseismic survey was carried out soon after each damaging shock. In some of the most damaged villages a building-to-building survey was carried out. Assessing the intensity during the campaign in the presence of increasing damage was one of the main problems to be dealt with. In this paper we present the data collected in Amatrice, Accumoli, Arquata del Tronto, and its expanded area called Borgo, after the 24th of August and the 30th of October earthquakes, in order to investigate the damage progression and its influence on the intensity assessment according to the European Macroseismic Scale (EMS-98). This work aims to document the evolution of the damage that was observed during the sequence in the above-mentioned areas, by analysing the behaviour of each vulnerability class, and to contribute to the discussion on the assessment of macroseismic intensity in presence of cumulative damage. [ABSTRACT FROM AUTHOR]

The seismic sequence which started on August 24th, 2016, caused hundreds of casualties, damage and collapses in four regions of Central Italy (Lazio, Umbria, Abruzzo and Marche). The strongest event, which occurred on October 30th (Mw 6.5), was forerun by four earthquakes with magnitude between 5.4 and 6.0. So far, a total of nine events with magnitude greater than or equal to 5.0 have taken place in the affected area. The earthquakes were caused by normal faults, all of them having NW–SE or NNW–SSE strike, approximately along the spine of the Apennine Mountains. The hypocentres of the events were at a shallow depth, between 8 and 10 km. The building stock in the affected area is mainly characterised by unreinforced masonry and reinforced concrete ordinary buildings, churches and historical constructions. Different municipalities, severely damaged, were not classified as seismic prone until 1981, or were originally attributed to a seismic zone with lower seismicity compared to the current one. This circumstance can explain, to a certain extent, the observed seismic response. In this study, aimed at interpreting the observed damage, the assessment of the damage potential of the ground motions recorded during the strongest events is performed by means of conventional and unconventional parameters. Specifically, elastic spectral demands, in terms of pseudo-accelerations, energies (equivalent velocity), displacements and rocking rotations are estimated, discussed and, whenever appropriate, compared with those of Italian seismic codes. Finally, different parameters related to the ground motion records destructiveness are calculated and compared with those obtained for other Italian earthquakes, highlighting how severe the 2016–2017 seismic sequence was. [ABSTRACT FROM AUTHOR]

Between August 2016 and January 2017 nine shallow earthquakes ranging from 5.0 and 6.5 of moment magnitude affected Central Italy, involving several municipalities wherein unreinforced masonry buildings are more than three quarters of all constructions. Damage state has been very severe, with sixteen settlements belonging to the municipalities of Amatrice, Arquata del Tronto, Accumoli, Castelsantangelo sul Nera and Norcia experiencing a cumulative European macroseismic scale intensity larger than IX. Ground motion demand in terms of peak ground velocity was approximately two or three times what expected for a 475 years return period while the pseudoacceleration response spectra showed values between once and twice gravity acceleration for the period range typical of two and three storeys unreinforced masonry buildings. Moreover, since October 2016, such large seismic demand acted on structures damaged from previous shocks testifying the effects of damage accumulation, too. The significant shaking alone cannot explain the extremely severe damage of some settlements, with large portions of whole blocks completely collapsed, highlighting the need for investigating the specific vulnerability factors and construction features of unreinforced masonry buildings in the affected area. In fact, although some deficiencies already highlighted in previous Italian earthquakes (e.g. inadequate structural connections) have been surveyed also during this sequence, a marked vulnerability of masonry and its mortar has been noticed, in particular in the area between Amatrice and Arquata del Tronto. On the contrary, the historical constructions in Norcia performed much better, as a result of the 1860 seismic code and of the retrofitting interventions implemented after the different earthquakes occurred in the last two centuries. Finally, a number of demolished and rebuilt constructions performed very well, and this was also the case also of modern hollow clay blockwork buildings that protected not only human life, but also cost of construction and continuity of use. [ABSTRACT FROM AUTHOR]

The seismic assessment of the vulnerability of existing public structures, especially school buildings, is a crucial issue in seismic prone countries. Recently, several national and regional programs and activities have focussed on the mitigation of Italian public buildings. They promote the scheduling of public buildings' structural safety assessment and, when needed, the design and execution of strengthening interventions. Nevertheless, the three strong earthquakes that occurred in the last decade in Italy, Abruzzo (2009), Emilia (2012), and Central Italy (2016), confirmed the vulnerability of school buildings and the social importance of their quick re-opening after a damaging earthquake. In the present paper, the activities carried out on 1514 school building structures in the aftermath of the 2016 Central Italy earthquake sequence are reported and analysed. According to survey data collected by post-earthquake usability inspections, the paper analyses the school buildings characteristics, damage level and extent to structural and non-structural components as well as the correlation between seismic intensity and observed damage. [ABSTRACT FROM AUTHOR]

The central Italy seismic sequence began in the latter half of 2016 and continued well into 2017, causing severe damage in the villages close to the source and causing hundreds of casualties. It is a sequence especially interesting to study, from the perspective of seismic actions experienced by structures, because it saw nine M ≥ 5.0 earthquakes within a period of 5 months, rupturing parts of the complex central Apennine mountain range fault system. Consequently, some of the main earthquake engineering issues that arose are the multiple locations where the code-mandated seismic actions were exceeded in more than one of the main events of the sequence and the number of pre- and low-code existing buildings that suffered heavy damage or collapse due to the intensity of individual earthquakes and the cumulative effect of repeated damaging shocks. The present article picks up on these topics and uses probabilistic seismic hazard, as well as the multitude of strong ground motion recordings available from the sequence, to provide a discussion on certain issues, that are all related to the topical subject of seismic actions. These issues are: (1) the unsurprising exceedance of code spectra in the epicentral areas of strong earthquakes; (2) the particular spectral shape and damaging potential of near-source, pulse-like, ground motions, possibly related to rupture directivity; and (3) structural non-linear behaviour in the wake of a sequence that produces repeated strong shaking without the necessary respite for repair and retrofit operations. [ABSTRACT FROM AUTHOR]

Seismic events that struck Italy in the last years had a dramatic impact on historical and cultural heritage. Damage occurred on existing masonry buildings, in particular on churches, stressed out the need to better understand the seismic behaviour of this type of constructions as well as to define more appropriate mitigation strategies to be applied at large scale. This study deals with a predictive methodology for vulnerability assessment of churches in large territorial areas. Focusing the attention on three naves churches of Abruzzi, the paper proposes modifications and integrations of an existing methodology taken by literature. These modifications are defined through a calibration procedure based on damage observation of 64 three naves churches located at different distances from the epicentre of the 2009 earthquake. The proposed model is employed to predict damage level distribution for different earthquake intensities, allowing fragility curves to be plotted and therefore potential damage scenarios to be represented. [ABSTRACT FROM AUTHOR]

The assemblage of a building inventory is necessary for the evaluation of seismic impact scenarios at the territorial scale. Building inventory, representing the distribution of building vulnerability classes at the territorial scale, could be performed at different levels of detail, depending on the size of the building stock, the territorial unit of analysis and on the adopted vulnerability model. Census-based data are usually employed as primary source for building inventory. A recent advancement towards compilation of regional scale inventories is provided by the interview-based Cartis approach, implemented in Italy within "Territorial themes" Reluis project, financed by the Italian Civil Protection Department. This paper proposes a first comparison of the results in terms of building inventory and the subsequent impact assessment that are obtained using Census (CE) and Cartis-based (CA) data for a town in southern Italy; a probabilistic framework for inventory is applied. Different vulnerability models are adopted and results compared. Moreover, a simple procedure that combines the informative levels present in the two approaches is proposed, allowing a mixed-type inventory from Census and Cartis data (CC) to be used for seismic impact assessment. Results of the application show that the inventory and related damage distribution changes as a function of the method adopted and in relation to the parameters considered for building classification in the vulnerability model. Comparing the impact in terms of a mean value of damage over the entire municipality, d m , calculated for various seismic intensities and starting from CE, CA and CC inventory, it is seen that the CC inventory is generally more conservative with respect to CA and CE for all the vulnerability methods, and a maximum scatter of approximately 45% in terms of d m is obtained for the considered application with one of the vulnerability methods. • The paper presents simplified methods to assemble building inventory. • Initial considered databases for building inventory are census returns and a newly developed interview-based database. • First comparison of the results on building inventory and damage assessment obtained using three types of building inventory. • Different vulnerability methods are considered for building classification and expected damage calculation. • The method is applied for a case study town in southern Italy. [ABSTRACT FROM AUTHOR]

The seismic sequence that struck central Italy from August to October 2016 caused severe damage to many historical and artistic buildings. In particular, churches were widely affected due to the intrinsic peculiarities of their structural system, unable to develop an efficient box-like resisting mechanism. After the seismic events, teams of experts carried out a massive survey of churches to assess both the occurred damage and their usability. Teams were coordinated by the Department of Civil Protection and the Ministry of Cultural Heritage. In this paper, a methodology for processing the data recorded during the inspections of a number of churches of the Marche region is proposed and used to analyse a sample data set. Starting from the subdivision of the sampled churches into homogeneous typologies, the most recurring damage mechanisms are identified. In addition, the global damage index of each church is correlated with the relevant highest pseudo spectral acceleration at period 0.30 s registered at the site as a consequence of the main shocks; relationships between the seismic intensity and the observed damage are then derived from such a correlation. Finally, the overall damage occurred to churches of the sample is compared to that estimated through empirical models available in the literature. [ABSTRACT FROM AUTHOR]

Earthquake is a natural calamity that cannot be predicted, and even though one day, hypothetically, this might be possible, its occurrence will not anyhow be avoided. Its unpredictability, together with its inescapability, poses the accent on preparedness and prevention, which represent the sole activities that can be pursued in order to mitigate its catastrophic effects. Within this scenario, human behaviour becomes extremely relevant. Two main actors of seismic risk mitigation are especially important: the population and the policy-makers, the latter in charge of safety and protection of the civil community. Contrary to a rational calculus, which would like people to protect themselves more and more as risk increases, we observe instances of inefficient behaviours, dictated to a large extent by the cognitive strategies with which people deal with when making decisions in the domain of seismic risk. Moreover, this expectation is largely unattended, because of the controversial behaviours and different perspectives of the two actors in dealing with seismic risk. The paper approaches the problem through the tools of behavioural economics, trying to investigate possible cognitive biases and risk misperception which can trigger crowding out either of individuals or policy-makers for undertaking seismic risk reduction measures, with the final goal of supporting and improving the effectiveness of risk reduction strategies designed at governmental level. A particular focus is dedicated to Italy, as being a country with high seismic risk and, on the other hand, significant skills on seismic risk reduction strategies. [ABSTRACT FROM AUTHOR]