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Assessment of churches based on empirical data at a territorial scale is a suitable tool to have an overview of the seismic behaviour of this peculiar structural typology and to evaluate their current state of vulnerability. Fragility and vulnerability curves are also aimed to perform the analysis of different seismic scenarios. The paper presents a detailed typological analysis of 633 single-nave churches, as a selected subset of the database previously examined by the authors, with the aim of evaluating more in detail the influence of some parameters, such as masonry typology, church dimensions and presence of the bell tower, on the vulnerability of the overall church. Then, specific analyses are carried out to assess the influence played by single mechanisms on the definition of the overall damage index, with the focus of providing qualitative evaluations and explicit vulnerability and fragility curves related to the most recurring and significant collapse mechanisms. This is an original contribution of the paper in the field of the vulnerability assessment of churches, since nowadays little information is available in the literature about the damage levels related to specific mechanisms, while most attention is still focused on global damage. [ABSTRACT FROM AUTHOR]

Earthquakes can generate large volumes of debris which may threaten public health, hinder reconstruction and impact the environment. The present paper aims at investigating how the current Italian regulatory framework may be further developed to improve communities' ability to manage debris from earthquakes. Since the lack of preparedness for managing disaster debris is not confined to Italy, the paper may be valuable to stimulate a broader debate on this issue. The research work is based on selected case studies (L'Aquila 2009, Regione Emilia-Romagna—Circolare n. 2 of 12.06.2012 (2012) "Provisions for the resumption of production activities according to art. 3 paragraphs 7 to 10 of Legislative Decree June 6, 2012 n. 74" and Central Italy 2016–2017 earthquakes) and the review of the relevant literature and legislation. It shows that preparedness could have contributed to reducing or avoiding significant delays and problems in managing debris after the above-mentioned Italian earthquakes. It further suggests that disaster debris management in Italy could benefit from the existence of a comprehensive ex ante regulatory framework including a range of different tools (laws, guidelines, contingency plans and the like) and from the proper implementation of laws that are already part of our legal order. The above findings may directly feed into decision-making addressing disaster debris management. Overall, the paper focuses on a research topic which is becoming increasingly relevant, given the rise in the number and severity of natural disasters, but which is still not widely explored. [ABSTRACT FROM AUTHOR]

In May 2012, two strong earthquakes hit the northern Italy revealing the significant seismic vulnerability of precast reinforced concrete structures and causing severe damage and many collapses, and high economic losses. After the lesson learnt from these events, more reliable seismic design criteria have been established for the design of new structures and different approaches have been proposed for the seismic assessment of the existing structures. In this context, the paper presents the results of a first application of the PRESSAFE-disp method, recently proposed by the authors, allowing to define the fragility curves of precast RC buildings at various limit states, including collapse. A stock of 91 precast buildings in the industrial area of San Felice sul Panaro (Modena) was selected as a benchmark case study to verify the reliability of the method in assessing seismic damage scenarios. In particular, with reference to the 2012 seismic ground-motion, two large-scale stochastic models are outlined to predict the number of the buildings collapsed in the area. The first one is based on a Monte Carlo simulation which incorporates the evaluation of the uncertainties, while the second one is a direct simplified calculation. Comparative considerations on the outcomes of the two methods for different seismic intensities are discussed, including the directionality effect of the ground-motion. To test the soundness of the simulations, the results of the two methods are compared with the real data collected through in-situ surveys. The procedures proposed here result, on average, in good agreement with the observed damage scenario. It is worth noting that, due to the inherent simplicity of the methods, they could be implemented to perform scenario-based seismic loss assessments to estimate the financial consequences of an earthquake affecting one or more industrial areas, and to drive the decision-making process for the seismic retrofit of existing precast RC buildings. [ABSTRACT FROM AUTHOR]

Structural elements, transversal to the Apennine chain, display various problematic aspects connected, above all, with their origin tectonogenetic role. From a seismic point of view, they may act as a structural barrier to the propagation of the Apennine normal faults or behave as transfer zones, thus activating neighboring segments belonging to the same fault system; the largest ones can also host significant earthquakes with the hypocenters located in the basement, below the Apennine thrust belt. This paper describes a case of recurrent surface faulting that reactivates a sector of a relevant transverse feature, the "." (FV-VE), near the city of Fabriano (Marche, Italy). Detailed geomorphological observations connect it with past earthquakes, including the disastrous event (I0 = IX MCS, about 6.2 Mw) of 24 April 1741 that struck the area with a wide distribution of damages extending along the Esino River Valley to the Adriatic coast over a distance of more than 50 km. Furthermore, paleoseismological analysis and radiocarbon datings of faulted river terraces and slope deposits, ranging in age from the end of the Middle Pleistocene to the recent Holocene, allowed us to define the evolutionary steps of the fault and estimate a slip rate of about 0.3 mm/year. [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]

This paper presents a comprehensive geological and geotechnical study of the whole area affected by liquefaction following the 2012 Emilia earthquakes, including all the available information from the field reconnaissance surveys, in situ tests, and laboratory analyses. The compilation was performed at 120 liquefied sites to verify and validate the reliability of liquefaction charts in alluvial sediments, and to assess liquefaction induced by the 2012 seismic sequence in the Emilia plain. The results reveal a wide range of grain sizes (from clean sands to sandy silts) and compositional characteristics (quartz-rich to litharenitic) in the 2012 ejecta, and show a strong relationship between the liquefaction and stratigraphic architecture of the subsurface. The availability of in situ tests at the liquefied sites makes it possible to verify and validate the reliability of the liquefaction charts in alluvial sediments with respect to the real observations. For the analyzed Emilia case studies, the use of non-liquefiable crust provides better estimations of the liquefaction manifestations when coupled with the thickness of the liquefiable layer rather than with the liquefaction potential index. Altogether, this work makes available to the international scientific community a consistent liquefaction database for in-depth earthquake studies. [ABSTRACT FROM AUTHOR]

Drawing on socio-psychology and economics literature contributions, this paper provides an original conceptual framework examining whether and how natural disasters exert any influence on nuptiality. Scholars suggest that disasters remind people about the transience of life and mortality. This feature triggers shifting towards intrinsic meaningful goals — such as commitment to relationships; at the same time, it fosters people's proximity and support-seeking from their security providing attachment figures and leads to accelerate life transition choices. In this view, disasters are expected to positively impact on people's intentions to marry. Such an effect is evident in case of natural hazards determining slight damage to physical capital (buildings, productive locations, etc.) which have limited economic consequences that do not hamper marriage intentions. Meanwhile, in the case of highly disruptive disasters, these positive psychological pushes are counterbalanced or even exceeded by the negative economic consequences of the disaster, which inhibit marriage intentions. These predictions are supported by an empirical analysis that relies on a difference-in-differences investigation of municipality-level nuptiality data collected in the Abruzzo region of Italy before and after the major 2009 L'Aquila earthquake. [ABSTRACT FROM AUTHOR]

Graphical techniques are recommended for critical applications because they allow for visual analysis and helpful understanding of the results, also for non-statisticians. However, 'graphical' estimation methods are often criticized because they are less efficient with respect to 'analytical' methods. This paper proposes a new general graphical method that leads to the best linear unbiased estimators of location-scale distribution parameters. Therefore, the reputation of graphical methods is raised and their strategic use is encouraged. An applicative example analyzes the earthquake magnitudes registered during the serious 1983-1984 bradyseismic crisis in Campi Flegrei, Italy. This graphical analysis will certainly work as a strategic reference picture to which the data, arising from the further bradyseismic crises expected in the next future, can be compared. [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 article focuses on earthquake reconnaissance missions and their benefits to earthquake engineering. Topics discussed in the article include achievements of early missions like the 1627 Gargano earthquake in Italy, contributions of UNESCO supported missions between 1963-1980 and modern post-earthquake field investigations along with investigating teams such as the German Task Force (GTF) and the Japanese Society for Civil Engineering (JSCE).

In this paper, we focused our attention on a cross-section of the Aterno River Valley where a good quality geological and geophysical dataset allowed to reconstruct accurately the geometry and the Vs profiles along all the plane of the section. Its trace is deliberately aligned close to the strong motion stations that recorded the Mw 6.3 (April 6th 2009) L'Aquila earthquake. We analysed strong and weak motion data available at these latter stations as well as at one of the temporary stations installed during the Microzonation activities and located on outcropping bedrock, in proximity of the cross-section. We used the H/V technique to select a reliable reference site and once we found it, we applied the SSR technique to compute amplification functions in correspondence of two strong motion stations. In turn, for both sites we performed a site response numerical modelling with two different 2D codes and we compared simulated versus experimental transfer functions. We found that the cross-section is well constrained based on the very reasonable agreement between results of numerical modelling and earthquake data analysis. We pointed out also a strong amplification of the deposit at the centre of the valley due to the constructive interference of S and surface waves, not predictable by means of 1D numerical modelling. We also compared the H/V as well as the SSR obtained from strong motion data with the ones computed from weak motion finding evidences of non-linearity in soil behaviour. [ABSTRACT FROM AUTHOR]

Despite significant research advances on the seismic response analysis, there is still an urgent need for validation of numerical simulation methods for prediction of earthquake response and damage. In this respect, seismic monitoring networks and proper modelling can further support validation studies, allowing more realistic simulations of what earthquakes can produce. This paper discusses the seismic response of the "Pietro Capuzi" school in Visso, a village located in the Marche region (Italy) that was severely damaged by the 2016–2017 Central Italy earthquake sequence. The school was a two-story masonry structure founded on simple enlargements of its load-bearing walls, partially embedded in the alluvial loose soils of the Nera river. The structure was monitored as a strategic building by the Italian Seismic Observatory of Structures (OSS), which provided acceleration records under both ambient noise and the three mainshocks of the seismic sequence. The evolution of the damage pattern following each one of the three mainshocks was provided by on-site survey integrated by OSS data. Data on the dynamic soil properties was available from the seismic microzonation study of the Visso village and proved useful in the development of a reliable geotechnical model of the subsoil. The equivalent frame (EF) approach was adopted to simulate the nonlinear response of the school building through both fixed-base and compliant-base models, to assess the likely influence of soil–structure interaction on the building performance. The ambient noise records allowed for an accurate calibration of the soil–structure model. The seismic response of the masonry building to the whole sequence of the three mainshocks was then simulated by nonlinear time history analyses by using the horizontal accelerations recorded at the underground floor as input motions. Numerical results are validated against the evidence on structural response in terms of both incremental damage and global shear force–displacement relationships. The comparisons are satisfactory, corroborating the reliability of the compliant-base approach as applied to the EF model and its computational efficiency to simulate the soil–foundation–structure interaction in the case of masonry buildings. [ABSTRACT FROM AUTHOR]

Site effects in consequence of the 2016–2018 Central Italy seismic sequence "marked the fate" of many villages located close to the epicenters along the Apennine chain. Pescara del Tronto, a small settlement located on a mountain slope in the municipality of Arquata del Tronto, (AP) is very representative of such territories since, early after the onset of the seismic sequence, suffered very impressive site effects, including a large seismically-induced debris flow and a high number of small volume landslides. This paper describes the main results of the scientific activities carried out by the authors in this locality in the framework of the unprecedented large-scale Seismic Microzonation project funded by Italian Government in Central Italy for 138 territories. Through an intense field activity, the geological and geomorphologic setting of the study area were revised and updated, including a landslide susceptibility assessment that helped the Italian Department of Civil Protection in the emergency management for temporary housing and, later on, was included in the 3rd Level Seismic Microzonation study implemented by authors while the seismic sequence was still ongoing. A very detailed and reliable subsoil model for this municipality was defined, despite difficulties faced in performing direct and indirect investigations due to the safety restrictions for many areas. The Local Seismic Site response was finally assessed for this locality and the results discussed. A key role in the occurrence of strong site effects into Pescara del Tronto has been played by quaternary deposits having an unexpected heterogeneity under the old village. [ABSTRACT FROM AUTHOR]

This study focuses on two weak points of the present procedure to carry out microzoning study in near-field areas: (1) the Ground Motion Prediction Equations (GMPEs), commonly used in the reference seismic hazard (RSH) assessment; (2) the ambient noise measurements to define the natural frequency of the near surface soils and the bedrock depth. The limitations of these approaches will be discussed throughout the paper based on the worldwide and Italian experiences performed after the 2009 L'Aquila earthquake and then confirmed by the most recent 2012 Emilia Romagna earthquake and the 2016–17 Central Italy seismic sequence. The critical issues faced are (A) the high variability of peak ground acceleration (PGA) values within the first 20–30 km far from the source which are not robustly interpolated by the GMPEs, (B) at the level 1 microzoning activity, the soil seismic response under strong motion shaking is characterized by microtremors' horizontal to vertical spectral ratios (HVSR) according to Nakamura's method. This latter technique is commonly applied not being fully compliant with the rules fixed by European scientists in 2004, after a 3-year project named Site EffectS assessment using AMbient Excitations (SESAME). Hereinafter, some "best practices" from recent Italian and International experiences of seismic hazard estimation and microzonation studies are reported in order to put forward two proposals: (a) to formulate site-specific GMPEs in near-field areas in terms of PGA and (b) to record microtremor measurements following accurately the SESAME advice in order to get robust and repeatable HVSR values and to limit their use to those geological contests that are actually horizontally layered. [ABSTRACT FROM AUTHOR]

This paper analyses data regarding the seismicity and ground deformations of the island of Ischia. The goal is to describe these phenomena as a space–time process, exploring the mechanism as a whole in order to answer questions concerning why and how historical earthquakes occurred and the geological constrains at the time of the earthquake of 21 August 2017. According to our analysis, the genesis of earthquakes in the island may be due either to regional tensile tectonics or to increased pressure in a shallow magma source. The eruptive rest following the 1302 Arso lava flow, the seismic silence from 1883 and the ground sinking recorded at least from the end of the nineteenth century suggest a decline of pressure in the shallow magma source and in the action of the stress field generated by the spreading of the Tyrrhenian Basin. The mechanism that can generate the observed ground deformation field and seismicity is the gravitational and thermal loading of the island, because the load of the massif of Mt. Epomeo onto its hot substratum may induce the gravitational spreading that would have produced its sliding southwards and its rotation northwards. The surface of detachment plunges towards the south and emerges at a high angle at the northern edge of Mt. Epomeo, where coseismic ground effects and the greatest damage have been observed. This mechanism that generated the 21 August 2017 earthquake could be extended to historical seismicity. [ABSTRACT FROM AUTHOR]

After the ML = 6.0 earthquake which occurred on 24th August 2016 in central Italy, some unexpected variability in the damage distribution were identified in many villages located around the epicentral area. In particular, despite a distance of only about 1300 m, the villages of Pescara del Tronto and Vezzano (both districts in the Arquata del Tronto municipality) had a different damage assessment. Pescara del Tronto suffered heavy damage, with many collapsed masonry buildings and 48 fatalities, whereas Vezzano suffered negligible to slight damage to a few buildings. This paper provides vulnerability and damage assessment in order to detect potential significant differences in the building vulnerability and damage level. Geophysical prospectings were performed to assess whether site effects could have increased the damage in Pescara del Tronto compared to Vezzano. [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]

This paper focuses on the structural performance of existing masonry and reinforced concrete bridges which were surveyed in the aftermath of the 2016 Central Italy earthquakes. Typical bridge vulnerabilities are first reviewed, as they provide a reference for the response of the bridges that were damaged by the 2016 earthquake swarm. Case studies are then discussed and preliminary numerical analyses are carried out to interpret the observed failure modes. In general, all surveyed masonry bridges experienced some extent of damage, particularly when built with poor-quality materials and subjected to geotechnical-induced effects. However, they offered a robust response in terms of collapse prevention. The majority of existing reinforced concrete bridges, although designed primarily for gravity loads, exhibited acceptable performance; however, local damage due to the poor maintenance of the structural systems was observed, which affected primarily the non-structural components of the bridges. [ABSTRACT FROM AUTHOR]

Damage scenarios for the main events of the 2016 Central Italy earthquake sequence have been simulated. In order to describe the seismic performance of the as-built in the area, the mechanic based method simplified pushover-based earthquake loss assessment has been adopted. This methodology has been extensively validated by means of comparison between numerically calculated damage scenario and observed damage. These data have been collected during the surveys in areas hit by earthquakes in Italy in the last 40 years (starting form 1976 Friuli earthquake until 2012 Emilia earthquake). The calculation of damage scenario has been performed in a user friendly WebGIS platform developed for the Italian Department of Civil Protection. The paper gives an overview of methods and informatics tools prior to present the results of the damage scenario. The results of damage scenarios are summarized in tables, charts and maps. Further, improvements of the tools now available are also identified for future developments. [ABSTRACT FROM AUTHOR]

Non-structural elements represent most of the total construction cost of typical buildings. A significant portion of the total losses in recent earthquakes worldwide, has been attributed to damage to non-structural elements. Damage to non-structural elements occurs at low levels of ground shaking, and can significantly affect the post-earthquake functionality of buildings. However, in Europe, limited prescriptions are provided in the codes for seismic design of non-structural elements and this may partially explain why it is so common for these elements to perform poorly during earthquakes. This paper describes the observed damage to non-structural elements following the 2016 Central Italy earthquake. The most commonly damaged elements were partition walls, ceiling systems, non-structural vaults, chimneys, and storage racks. As a result, it was highlighted the need to introduce seismic regulations devoted to improving the seismic performance of non-structural elements and to reduce the associated economic losses, loss of functionality, and potential threats to life safety. [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]

This paper shows how mature and consolidated scientific outcomes and the increased awareness on the risks related to the hydrocarbon production and gas storage have brought European and national governments to develop new regulations, decrees, and guidelines informed by high-level scientific contents. To do this, the Italian experience from 2012 to present is described from the viewpoint of two governmental administrations, i.e., the Ministry of the Economic Development and the National Civil Protection Department. A fruitful interaction among research institutes, universities, and public administrations has accompanied this long activity phase. It includes, among other things, the constitution of working groups, the development of regulatory guidelines, their testing in pilot case studies, the constitution of a technical-scientific network for the offshore safety (CLYPEA). Within this collaboration, common goals are pursued with a coordinated approach by the ministry and the department, optimizing therefore the achievement of common goals. [ABSTRACT FROM AUTHOR]

The prediction of the variability of the seismic ground motion in a given built-up area is considered an effective tool to plan appropriate urban development, to undertake actions on seismic risk mitigation and to understand the damage pattern caused by a strong-motion event. The procedures for studying the seismic response and the seismic microzonation of an urban area are well established; nevertheless, some controversial points still exists and are discussed here. In this paper, the selection of a reference input motion, the construction of a subsoil model and the seismic response analysis procedures are discussed in detail, based on the authors' experience in two Italian case histories: the seismic microzonation of the city of Benevento, which was a predictive study, and the simulation of seismic response and damage distribution in the village of San Giuliano di Puglia, which was a retrospective analysis. [ABSTRACT FROM AUTHOR]

A series of earthquakes, the highest of magnitude $$\text{ M }_\mathrm{w}$$ 5.9, hit a portion of the Po Valley in Northern Italy, which was only recently classified as seismic. The paper reports the findings and the lessons learnt from a preliminary field survey which was conducted immediately after the second event. As a result of the economic attitude of the affected area, and possibly of the characteristics of the event, an unprecedented number of industrial precast buildings were affected, resulting into most of the casualties as well as in large economic losses. Whereas most of the damaged and collapsed buildings were designed for gravity loads only, evidence of poor behavior of some precast buildings designed according to seismic provisions were discovered. The paper provides a description of the performance of precast buildings, highlighting the deficiencies that led to their poor behavior as well as some preliminary recommendations. [ABSTRACT FROM AUTHOR]

The earthquake sequence started on May $$20$$ th 2012 in Emilia (Italy) affected a region where masonry constructions represent a large part of the existing building stock and the construction of new modern masonry buildings is a common practice. The paper is focused on the performance of common architectural configurations, typical for residential or business use. The large majority of old masonry buildings is made of fired clay bricks. The seismic performance of these buildings is particularly interesting since major past earthquakes in Italy affected areas with mainly stone masonry structures. Apart from examples showing systematic or peculiar structural deficiencies governing the vulnerability of several buildings, the overall seismic performance of these structures to repeated shaking, with PGA as large as 0.25-0.3 g was rather good, despite the major part of them were only conceived for carrying vertical loads. In fact, seismic design is mandatory in the area only since 2003. Modern low-rise masonry buildings erected after this date and incorporating seismic design and proper detailing resulted in most cases practically undamaged. The examples reported in the paper allow an evaluation of the superior performance of seismically designed modern masonry buildings in comparison to older ones. [ABSTRACT FROM AUTHOR]

In recent years, numerous natural disaster affected the Italian territory, growing the demand of secure on-field procedures able to accomplish the task of reconnaissance, inspection and survey of instable infrastructure and cultural heritage. During the early-impact there are numerous first response figures, like firefighters, civil protection, geotechnical inspectors and surveyors, that have to operate nearby damaged structure putting at risk their lives in case of possible collapses. Most of these operators work in heavy conditions, so they need tools and procedures that allow them to rush into decisions. These procedures must be rapid, easy to use and must allow the possibility to conduct the task with a certain distance of the instable or not easily accessible structures. This paper deals with the use of tablet devices for rapid close range photogrammetry in post-earthquake scenario, following the close range photogrammetry approach. Starting from images acquired by tablets during speditive surveys, the authors show how is possible to reconstruct the environment starting from data acquired by low cost devices. The case-study considered in this work is the Sant’Agostino Church in Amatrice (Italy), a cultural heritage highly damaged by the 6.0 magnitude earthquake occurred on 24 August 2016 in the central part of Italy. [ABSTRACT FROM AUTHOR]

This paper presents the Virtual Research Environment (VRE) enabling two European GEO Geohazard Supersites in Italy. According to GEO (Group on Earth Observation) vision, Geohazard Supersites provide access to spaceborne and in-situ geophysical data and models for selected sites prone to natural hazards -noticeably, earthquakes and volcano eruptions. The VRE was implemented in the framework of the Mediterranean Supersite Volcanoes (MED-SUV) project, funded by the European Commission. MED-SUV realized one of the European supersite demonstrators covering the two Permanent Supersites selected in Italy: Mt. Etna and Campi Flegrei/Vesuvius. The MED-SUV VRE provides advanced services for heterogeneous data and information management and sharing. MED-SUV started identifying the main supersite requirements including: the interoperability with existing data/information supply systems, the support of policy-based access control, the access to processing capabilities provided by external platforms, the management resources for publishing and sharing new products, the integration with significant global systems such as GEOSS and EPOS. MED-SUV adopted a System of Systems (SoS) approach to address interoperability with the identified heterogeneous systems supplying data and information. The SoS approach is based on a brokering architecture, where a specialized component (i.e the MED-SUV Broker: MSB) connects the existing and next-coming data sources leaving them autonomous. MSB carries out all the necessary mediation and harmonization tasks exposing standard interfaces enabling the interconnection with external systems like GEOSS and EPOS. In addition, MSB is accessible via a JavaScript library implementing Web APIs to facilitate the development of Web and mobile applications. [ABSTRACT FROM AUTHOR]

In this paper, we separate the residuals of ground motion prediction equations into different components, calculating the repeatable site-specific ( $$\delta S2S_{s}$$ ), location-specific ( $$\delta L2L_{r}$$ ) and path-specific ( $$\delta P2P_{er}$$ ) correction for the median model. In this way, we can reduce the total standard deviation (sigma) of the ground-motion model by Lanzano et al. (Bull Seismol Soc Am 106(1):73-92, 2016), removing these components and overcome the ergodic assumption. These repeatable terms are empirically estimated using a dataset composed by acceleration waveforms of Italian events mainly occurred in the Po plain and Eastern Alps (Northern Italy), in the time interval 1976-2015. The analysis is carried out on 2241 recordings, from 88 shallow earthquakes recorded by 168 sites. A local model, specifically tailored for Northern Italy, is used as the reference GMPE, which predicts the geometric mean of the horizontal peak ground accelerations and response spectral ordinates in the period range 0.04-4 s. Because most of the propagation paths sampled only once, the path-specific components and the resulting aleatory variability are also calculated from the spatial correlation of residuals, following the approach of Lin et al. (Bull Seismol Soc Am 101(5):2281-2295, 2011). We find a significant reduction of the overall ground motion variability to an extent comparable to what observed from previous studies on empirical and simulated datasets. The estimated median corrections and variance components can be used in probabilistic seismic hazard assessment for a single site and a single path in Northern Italy. As an example, we compute the hazard curves at some sites by means of three different approaches (ergodic, partially non-ergodic and full non-ergodic), in order to quantify the impact of relaxing the ergodic assumption. [ABSTRACT FROM AUTHOR]

L'Aquila earthquake, which occurred on April 6, 2009, proved the high vulnerability of cultural heritage, with particular reference to churches. Damage assessment in the emergency was carried out on more than 700 churches with a methodology aimed at recognizing the collapse mechanisms in the different architectonic elements of the church. The method was developed after the earthquake in Umbria and the Marches (1997) and has been widely used in the last decade; this approach is also very useful for seismic prevention, as it allows one to single out the most vulnerable structures. Some examples are presented in this paper, representative of recurrent damage in the main elements of the church: the façade, the roof, the apse and the belfry. It emerges that, for a correct interpretation of damage and vulnerability, it is necessary a deep knowledge of local construction techniques and of the historic transformation sequence. Moreover, the bad behaviour of churches strengthened by modern techniques, such as the substitution of original timber roofs with stiff and heavy r.c. slabs, was observed. Starting from the observation of some case studies, the paper achieves some worth results, which may be useful for correctly driving future strengthening interventions. [ABSTRACT FROM AUTHOR]

This paper presents the results of a systematic historical study of the seismic, bradyseismic and eruptive activity of the Campi Flegrei caldera. The aim is to make a revised historical data available for accurate volcanological interpretation, supplying additional data and highlighting spurious previous data. The analysis begins with the supposed 1198 eruption, which did not actually take place. No information is available for the thirteenth and fourteenth centuries. As far as the fifteenth and sixteenth centuries are concerned, only direct sources were examined for this paper, and they include many different types of evidence. The chronological breadth of the analysis has also provided information about the seismic crises and bradyseisms prior to the eruption of 1538. The exceptional nature of this 1538 eruption attracted the attention of intellectuals, diplomats and natural philosophers, who left valuable accounts, which we have analysed, and which include many that are still available in their original manuscript form. The previous studies concerning the 1538 eruption were based on 23 (variously used) sources. We have examined 35 additional sources bringing the overall corpus of sources analysed to 58. The results provide a more precise scenario of events preceding the 1538 eruption, including bradyseismic activity starting from the end of the fifteenth century. The chronology of the phenomena described comprises the core result of this study, and has been constructed so as to clarify the time, location and impact of each event. For the 1538 eruption, a countdown is included which may also have a predictive value. For the last 36 hours before eruption began, the countdown is hour-by-hour. The effects of the eruption and earthquakes on people, structures and society are also described for Pozzuoli, Agnano and Naples. The areas where heavy materials and ash fell are likewise indicated, as well are the earth tremors felt by the population from the eruptive crisis up to 1582. [ABSTRACT FROM AUTHOR]

The architectural heritage was severely damaged by the seismic sequence that occurred in Emilia (Northern Italy) in May 2012. This paper investigates the seismic behavior of three masonry churches that were damaged by the 2012 Emilia earthquake. The analyzed churches are located in the South-East area of the province of Mantua: they are representative of some churches, denoted as 'Matildic churches', belonging to the territorial area between Lombardia, Emilia Romagna and Toscana and built during the Matilde di Canossa domain, between the X and the XI centuries. The study was based on detailed field surveys, in situ tests, visual inspections and existing archives in order to obtain an accurate knowledge of the churches and a proper evaluation of the damage caused by the earthquake. Then, detailed finite element models of the churches were developed and non-linear dynamic analyses with different peak ground accelerations were performed. The numerical simulations provided a deep insight into the seismic behavior of the analyzed churches, identifying the damage patterns and the main collapse mechanisms for different seismic intensity levels. The obtained results appear to be in a good agreement with the damage experienced by the churches during the earthquake. This study can be considered as a first step to assess the seismic vulnerability of the 'Matildic churches', extremely important for their historical and architectural value. [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]

In this paper, we address the issue of evaluating the seismic site response for sites located on large alluvial plains, for which no reference sites can be identified, but some earthquakes can be simultaneously recorded at both surface and depth. In the proposed method, surface and borehole records are firstly used to assess the local 1D velocity model, then a model representing a virtual reference rock site is defined, and finally the site spectral amplification is calculated through numerical modeling. The effectiveness of the method is demonstrated at the site of Mirandola (Italy). This site is located in an area which suffered heavy damage during the seismic sequence that started in Northern Italy with the Mw = 5.8 event on May 20th, 2012. That time, the site hosted an accelerometer of the National Accelerometric Network, which recorded the whole sequence. A new station, named MIRB (MIRandola Borehole), was installed during 2014; it is equipped with three accelerometric sensors deployed at surface, 31 and 126 m depth, respectively. The results of this study evidence that Mirandola is characterized by an amplification level consistent with that of a class-C soil for up to a period of about 0.45 s, while for higher periods, the amplification lays between class-B and C soils. [ABSTRACT FROM AUTHOR]

For important facilities, such as hospitals or schools, advanced seismic risk assessment methodologies have been developed and are now available for use by owners and facility managers. These include seismic hazard analysis coupled with structural and non-structural response and damage analyses leading to a final consequence analysis that provides indications of performance measures, which are often referred to as decision variables. Typical decision variables are repair costs, probability of collapse of the entire building and downtime. These decision variables do not provide specific information regarding the likelihood of individual rooms to remain functional after an earthquake. For the case of a hospital, for example, information regarding the functionality of specific critical rooms (e.g. operating or emergency rooms) could influence major design/retrofit decisions by the owner or facility manager. The main objective of this paper is to present, through a case study hospital building in Italy, a methodology for assessing the loss of functionality of individual rooms in critical facilities following an earthquake event. The methodology includes all the aspects that are usually considered individually in seismic risk assessment, such as ground motion selection for probabilistic seismic hazard analysis, structural performance of the building, and the performance of non-structural elements that can affect the functionality of selected rooms. [ABSTRACT FROM AUTHOR]

A comprehensive comparison among the three strongest earthquakes occurred in Italy in the past 30 years is presented. These three earthquakes struck the regions of Umbria and Marche in 1997, Abruzzo in 2009, and Emilia-Romagna, Lombardia and Veneto in 2012, respectively. They were assigned exactly the same local magnitude, Ml5.9, and comparable focal depths. In spite of having occurred in the same country, these earthquakes displayed considerable differences from both the scientific and the civil protection points of view. Differences can be ascribed to the released energy, the seismotectonic and geomorphological features, as well as the diverse population density, building features and socio-economic conditions that characterize the three epicentral areas. Nevertheless, the overall economic losses come out to be almost the same, although deriving from quite diverse distributions among the different categories of costs. Differences and similarities among the three events are carefully analysed and discussed in the paper. [ABSTRACT FROM AUTHOR]

After the seismic events of the 20th and 29th of May 2012 in Emilia (Italy), most of the monumental and historic buildings of the area were severely damaged. In a few structures, partial collapse mechanisms were observed (e.g. façade tilting, out-of-plane overturning of panels...). This paper presents the case-study of the bell tower of the Santa Maria Maggiore cathedral, located in Mirandola (Italy). The dynamic response of the structure was evaluated through operational modal analysis using ambient vibrations, a consolidated non-destructive procedure that estimates the dynamic parameters of the bell-tower. The dynamic tests were carried out in pre-intervention and post-intervention conditions in order to understand the sensitivity of dynamic measurements to safety interventions. Furthermore, a comparative study is made with similar cases of undamaged masonry towers up to the 6th mode. Finally, an investigation on the state of connections and of the building itself is carried out via FE model updating. [ABSTRACT FROM AUTHOR]

The seismic crisis that hit Calabria (South Italy) since the beginning of 1783, lasted 3 years with strong earthquakes concentrated in the first 2 months, causing many fatalities and great destruction, as reported by several detailed historical reports. Following an earthquake that occurred on February 6, 1783, a mass with volume of about 6 Mm detached from the flank of Mount Pacì and collapsed into the sea. In 1 min, huge waves attacked the nearby village of Scilla and killed most of the people that had gathered in the wide shore named Marina Grande to escape from seismic danger. More than 1500 people died due to the tsunami, many buildings were destroyed. In the paper, such catastrophic event is studied by means of numerical models. First we reconstruct the initial sliding mass and compute its motion through a Lagrangian model; then, we simulate the tsunami generation, propagation and flooding on the coast of Scilla by means of a nonlinear shallow-water equations model. The results of the simulation are compared against the detailed description of the tsunami effects available from several historical accounts and are found to be in a very satisfactory agreement with the 6-8 m inundation height reported in the Marina Grande beach. [ABSTRACT FROM AUTHOR]

Stochastic models of point patterns in space and time are widely used to issue forecasts or assess risk, and often they affect societally relevant decisions. We adapt the concept of consistent scoring functions and proper scoring rules, which are statistically principled tools for the comparative evaluation of predictive performance, to the point process setting, and place both new and existing methodology in this framework. With reference to earthquake likelihood model testing, we demonstrate that extant techniques apply in much broader contexts than previously thought. In particular, the Poisson log-likelihood can be used for theoretically principled comparative forecast evaluation in terms of cell expectations. We illustrate the approach in a simulation study and in a comparative evaluation of operational earthquake forecasts for Italy. [ABSTRACT FROM AUTHOR]

Electromagnetic emissions in thermal infrared bands are an important research topic on pre-earthquake studies. Satellite thermal data have been investigated by many independent research groups looking for their anomalous behaviour before main earthquake's occurrences. Among them, geosynchronous satellite data are reported as less prone to artefacts during data processing. In this work, the Night Thermal Gradient (NTG) algorithm is presented, which has been specifically proposed for geostationary thermal infrared data processing. NTG method relies on the exploitation of high temporal resolution data to find coherent low frequency components of a hypothetical precursory signal of seismic activity. In this paper, the method is presented by giving details about the applied procedures, steps, theoretical assumptions and results obtained during the studies of L'Aquila 2009 earthquake and the seismic activity of Central Italy and Sardinia. [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]

A new approach in dealing with seismic risk in the volcanic areas of Italy, by taking into account the possible occurrence of damaging pre- or syn-eruptive seismic events, is exciting the scientific interest and is actually the topic developed in several research projects funded by the European Community (e.g., UPStrat-MAFA, ) and the Civil Defense Department of Italy. To achieve this goal, it is necessary to have a detailed knowledge of the local attenuation-distance relations. In the present paper, we make a survey of the estimates of the seismic quality factor of the medium reported in literature for the Etna area. In the framework of a similar paper published for the Campi Flegrei zone in Southern Italy, we first review the results on seismic attenuation already obtained for Etna and then apply a standard technique to separately measure intrinsic and scattering attenuation coefficients from passive seismic data recorded by the Etna seismological network. Indications are then given for the correct utilization of the attenuation parameters to obtain the best candidate quality factor Q to be used in this area for seismic risk purposes. [ABSTRACT FROM AUTHOR]

This paper outlines the response of the healthcare system in the area mainly affected by the 2012 Emilia earthquake by drawing on specific surveys and information from local health authorities. Some hospitals were evacuated after the M $$_\mathrm{l}$$ = 5.8 May 20 seismic event due to damage to non structural components and minor structural damage. A short description of the damage suffered and characteristics of the healthcare system as a whole is offered initially, followed by a detailed description of the effects which took place at the Santa Maria Bianca hospital of Mirandola. The focus has been on damage to non structural elements and content, whose integrity is of primary importance for healthcare structures performance during and after a seismic event. Some instruments for the acquisition of accelerometric data were installed after the May 20 event both outside and inside a building which is part of the hospital complex. The seismic behavior of this building has also been analysed by means of a purposely made finite element model and on the basis of the recorded data. The contribution of undamaged and damaged masonry infills to the global seismic response has also been estimated thus providing some hints on the observed building performance. [ABSTRACT FROM AUTHOR]

A complex seismic sequence characterised by two thrust earthquakes of magnitudes M $$_\mathrm{L}$$ 5.9 and M $$_\mathrm{L}$$ 5.8 occurred on May 20 and 29, 2012, respectively, and activated the central portion of the Ferrara Arc structure beneath the Po Plain in northern Italy. The sequence, referred to as Emilia 2012, was recorded by the Italian Strong Motion Network, the Irpinia Network, the Friuli Venezia Giulia Network and 15 temporary stations installed by the Civil Protection Department. In this study, we compile and analyse a large dataset that contains 3,273 waveforms from 37 $$M_\mathrm{L} \ge 4.0$$ seismic events. The main aim of this paper is to characterise the ground motion induced by the Emilia 2012 seismic sequence and compare it with other data in the Italian strong motion database and to the recent Ground Motion Prediction Equations (GMPEs) developed for northern Italy, all of Italy and Europe. This is achieved by (1) the computation and analysis of the strong motion parameters of the entire Emilia Strong Motion Dataset (ESMD) and (2) a comprehensive investigation of the May 29 event recordings in terms of time-frequency analysis, the ground motion parameters and the response spectra. This detailed analysis was made possible by the temporary Civil Protection Department stations that were installed soon after the May 20 event at several municipalities in the epicentral area. Most of the recordings are characterised by low-frequency content and long durations, which is a result of the thick sedimentary cover that is typical of the Po Plain. The distributions of the observed horizontal peak ground accelerations and velocities (PGAs and PGVs) with distance are generally consistent with the GMPEs. This is particularly true for the data from M $$_\mathrm{L} \ge $$ 5.0 (M $$_\mathrm{W}\ge $$ 5.0) events, though the data are scattered at distances beyond approximately 60-70 km and show faster attenuation than the European GMPEs. The horizontal components for the May 29 event at two near-fault stations (Mirandola and San Felice sul Panaro) are overestimated by all of the analysed GMPEs. In contrast, the vertical components, which played an important role in the shaking near the source, are underestimated. The May 29 event produced intense velocity pulses on the horizontal components and the highest peak ground acceleration ever recorded in Italy on the vertical component of the Mirandola near-fault station. The ground motion recordings contained in the ESMD significantly enrich the Italian strong motion database. They contribute new information about (1) the possibility of exceeding the largest recorded PGA in Italy, (2) the development of a spectral design that takes into account the role of the vertical component and the extreme variability of the near-fault ground shaking, and (3) the characterisation of the ground motions in deep sedimentary basins. [ABSTRACT FROM AUTHOR]

This paper addresses the structural damage to the main buildings of the cities of Reggiolo and Carpi after the primary earthquake shocks on May 20th and 29th, 2012, in Emilia Romagna. The damage survey, performed via form-based methods, highlights the different seismic behaviour of several types of buildings, especially those having historical features, and the consequences of the damage in terms of costs. Moreover, an analysis of some failure mechanisms activated in Reggiolo enables the evaluation of the local peak ground acceleration, due to the soil amplification. [ABSTRACT FROM AUTHOR]

Vernacular buildings are a relevant part of the building stock affected by the Emilia, 2012, earthquakes and they contribute to shape the rural landscape of the Po valley. Unfortunately, due to overall layout, constructive details and poor maintenance, they have shown a very poor seismic performance. Because most of these buildings are lightly used or abandoned, the risk that they will be demolished is rather high; this could be the most long-lasting outcome of the seismic sequence, deeply affecting the traditional landscape of this portion of the Po valley. In this paper a brief description of the architectural features of these buildings is given and their typical seismic performances are analysed. Because damage is usually related to local-collapse mechanisms, rocking spectra are computed for the near field accelerograms and they are compared with observed behaviours. Finally, suggestions are given to improve the earthquake response of these structures, with the aim of preserving important testimonies of the civilisation of the area. [ABSTRACT FROM AUTHOR]

The geothermal field of Torre Alfina is located in central Italy at the northern edge of the Vulsini Volcanic District, the northernmost area of the so-called Quaternary Roman Co-Magmatic Province. In the framework of a medium-enthalpy geothermal exploitation project, INGV installed a local seismic network close to the future geothermal production site for monitoring natural local seismicity. In this paper, we show the results of a study of the microseismicity recorded from June 2014 to May 2016 in a small area of about 10 km2 around Torre Alfina. Analyzing seismic signals recorded by a local temporary network of ten short-period stations and by four permanent stations of the INGV national seismic network, we detected 846 local earthquakes. Then, we accurately relocated 799 events using HypoDD code. Our results show that the region of Torre Alfina is characterized by intense microseismicity, with hypocentral depths between 3 and 7 km and with moderate magnitudes between Md = 0.1 and ML = 2.8. Moreover, more than half of the earthquakes are grouped into six main swarm-like clusters each lasting few days. Furthermore, we computed 36 well-constrained fault plane solutions, which show a clear transtensional deformation regime in the whole study area. Three main tectonic directions have been evidenced from the focal mechanisms analysis: E-W, WSW-ENE, and NW-SE. The understanding of the seismogenic structural setting of the Torre Alfina geothermal field, and the study of its background natural seismicity can be of great importance in recognizing any possible future seismicity induced by the exploitation of the field. [ABSTRACT FROM AUTHOR]

Population displacement is one of the most common consequences of disasters, and it can profoundly affect communities and territories. However, gaining an accurate measure of the size of displacement in the days and weeks following a major disaster can be extremely difficult. This study uses aggregated Call Detail Records as an inexpensive and efficient technique to measure post-disaster displacement in four Italian regions affected by repeated earthquakes in 2016–2017. By comparing post-disaster mobile phone count with a forecast computed before the earthquake hit, we can compute an index of change in the presence of mobile phones (MPE). This measure, obtained thanks to advanced analytical techniques, provides a reliable indication of the effect of the earthquake in terms of immediate and medium-term displacement. We test this measure against census data and in combination with other datasets. Looking into available data on economic activities and requests for financial support to rebuild damaged buildings, we can explain MPE and identify significant factors affecting population displacement. It is possible to apply this innovative methodology to other disaster scenarios and use it by policymakers who want to understand the determinants of population displacement. [ABSTRACT FROM AUTHOR]

Geophysical data provide the chance to investigate a volcano's dynamics; considerable information can especially be gleaned on the stress and strain patterns accompanying the internal processes and the effect of magma ascent on the main structures triggering earthquakes. Here, we analysed in detail the seismicity recorded over the last two decades on Etna volcano (southern Italy), focusing on earthquakes distribution and focal mechanism clustering; the ground deformation pattern affecting the volcanic edifice with the inflation and deflation phases was also examined. Analysed data were compared in order to shed light on possible relationships with the volcanic activity and to better understand the internal dynamics of the volcano over time. Significant steps during or shortly before major eruptions in the seismic strain release and ground deformation temporal series highlight a straightforward relationship between seismicity occurring at shallow level, inflation/deflation and volcanism. Furthermore, at depths greater than 5–7 km, down to about 20 km, the orientation of the P- and T-axes clearly indicate the existence of a pressure source in the central part of the volcano. All the results underline that the stress field related to the volcano plumbing system interferes with the regional field, partly overriding it. [ABSTRACT FROM AUTHOR]