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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 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]

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]

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 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]

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]

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]

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]

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]

In this paper we describe the macroseismic effects produced by the long and destructive seismic sequence that hit Central Italy from 24 August 2016 to January 2017. Starting from the procedure adopted in the complex field survey, we discuss the characteristics of the building stock and its classification in terms of EMS-98 as well as the issues associated with the intensity assessment due to the evolution of damage caused by multiple shocks. As a result, macroseismic intensity for about 300 localities has been determined; however, most of the intensities assessed for the earthquakes following the first strong shock on 24 August 2016, represent the cumulative effect of damage during the sequence. The earthquake parameters computed from the macroseismic datasets are compared with the instrumental determinations in order to highlight critical issues related to the assessment of macroseismic parameters of strong earthquakes during a seismic sequence. The results also provide indications on how location and magnitude computation can be strongly biased when dealing with historical seismic sequences. [ABSTRACT FROM AUTHOR]

Investigating relationships between macroseismic intensity and strong-motion data requires the existence of these two records for the same seismic event and site. In Italy, this comparison is feasible through the cross-matching of the Italian Macroseismic Database (DBMI) and the Italian Strong-Motion Database (ITACA) which are the most comprehensive sources of both data. However, the two databases lack a direct link which would allow performing joint analysis of macroseismic data points and strong-motion recordings, making the comparison a time consuming job for the researcher. This paper demonstrates the usefulness of cross-database identifiers, and presents their use in a web-tool called Rosetta, an initial proof-of-concept that helped testing linking procedures among DBMI and ITACA, and user friendly visual solutions. The development allowed the working group to exchange expertise on their respective database structures and workflows, laying the groundwork for a consistent, low-maintenance, and durable solution that will be easily updatable each time a new version of DBMI or ITACA will be released. [ABSTRACT FROM AUTHOR]

Soon after the earthquake that damaged L'Aquila municipality and its Province in the Abruzzi Region, Italy, on the 6th of April 2009, a widespread damage and usability assessment of buildings was launched. In 3 months, about 70,000 buildings were inspected, with the AeDES form, by public servants and professionals coordinated by the Italian Civil Protection Department. The paper, after describing the procedures and the form that were used for the assessment, discusses the time evolution of the inspections and analyses the data on building type and seismic damage. The empirical damage distribution conditional upon seismic intensity and building type is provided and the role of several vulnerability factors, such as the quality of masonry, the construction year, the number of stories, and the pre-existing damage, is highlighted. Lastly the damage consequences, such as the immediate occupancy conditional upon building damage and building type, are reported. [ABSTRACT FROM AUTHOR]

This paper overviews the procedures and tools used for a systematic study of the macroseismic consequences caused by a strong earthquake that struck Southern Italy. The event referred to the 23 November 1980 (Io = X MCS, Ms = 6.9) which affected the Campania and Basilicata regions. Two aspects are addressed here: to broaden the knowledge of the macroseismic field and delineate damage maps of the sites affected on an urban scale. The target area of this study is the Basilicata region about which the current macroseismic information is poor. This research study, based only on unpublished documentary sources, supplies about 50 new assessments and about 30 new re-assessments of the macroseismic site intensity (MCS scale) as outputs. Moreover, about 80 thematic maps showing the damage pattern of the sites affected are also supplied. It is the first time that a large earthquake has been the subject of such extensive studies from a macroseismic point of view, with special attention to the analysis of damage effects at town scale. [ABSTRACT FROM AUTHOR]