Vulnerability of Building, urban infrastructure and system: The case of Mt. Etna

Natural disasters, such as earthquakes and volcanoes, have strong effects on the socio-economic wellbeing of countries and their people. The consequences of these events can lead to complex cascades of related incidents; when these expand across sectors and borders, and in more serious contexts, they can threaten our basic survivability. These events have clearly demonstrated that preparedness and disaster management is a dynamic process that requires a holistic analysis of critical interdependencies among core infrastructures. In this context of complexity, uncertainty and doubt, the Disruption Index (DI) proposed in the framework of the UPStrat-MAFA project aims to improve our understanding of earthquake and volcano hazards and their impacts. Several guiding principles and methods have been developed to serve as the basis to measure the different earthquake impacts, with analysis and discussion of the data that provide clearer pictures of how the systems and the disruption of their functionality affect an urban area. The main concepts that explain the DI can be found in Ferreira et al. (2014). Constructing the DI requires good quality information about the physical, spatial and vulnerability conditions of the study area; this means the information that reflects the full knowledge of the true situatio

Bayesian analysisof a probability distribution for local intensity attenuation

Intensity attenuation and its variation as a function of the distance and earthquake size is still a critical issue in evaluating seismic hazard. We present a method that allows us to incorporate additional information from the historical earthquake felt reports in the probability estimation of local intensity attenuation. The approach is based on two ideas: a) standard intensity versus epicentral distance relationships constitute an unnecessary filter between observations and estimates; and b) the intensity decay process is affected by many, scarcely known elements (the physical parameters of the source, propagation path effects, building vulnerability, the semi-qualitative character of macroseismic scales, etc.). Hence intensity decay should be treated as a random variable as is the macroseismic intensity. We assume here that decay, defined on the set {0,1, ..., I0}, follows a binomial distribution with parameters (I0, p); p depends on the distance from the epicenter and is related to the probability of null decay at that distance. According to the Bayesian approach this p parameter is, in turn, a Beta random variable. The observations related to earthquakes with their epicenter outside the area concerned, but belonging to homogeneous zones, are used as prior knowledge of the phenomenon, while the data points of events inside the area are used to update the estimates through the posterior means of the quantities involved. Our methodology is described in detail in an application to the Umbria-Marche area in Central Italy. The data sets examined are the macroseismic intensity database DOM4.1 and the zonation ZS.4, both compiled by the Italian Group for Defence against Earthquakes (GNDT). The method is validated by comparing the observed and the estimated intensity data points of the Camerino (28/07/1799) and of the Colfiorito (26/09/1997) earthquakes

Analysis of strong ground motions to evaluate regional attenuation relationships

Italian attenuation relationships at regional scale have been refined using a data set of 322 horizontal components of strong ground motions recorded mainly during the 1997-1998 Umbria-Marche, Central Italy, earthquake sequence. The data set includes records generated by events with local magnitude (M L ) ranging between 4.5 and 5.9, recorded at rock or soil sites and epicentral distance smaller than 100 km. Through a multiple step regression analysis, we calculated empirical equations for the peak ground acceleration and velocity, the Arias Intensity and for the horizontal components of the 5% damped velocity pseudo response spectra, corresponding to 14 frequencies ranging from 0.25 to 25 Hz. We compared our results with well known predictive equations, widely used on the national territory for Probabilistic Seismic Hazard Analysis. The results obtained in this study show smaller values for all the analyzed ground motion indicators compared to other predictive equations

Applying the Disruption Index procedure to evaluate the urban seismic risk in the Mt. Etna area (Italy)

The Disruption Index is used here for the assessment of urban disruption in the Mt. Etna area after a natural disaster. The first element of the procedure is the definition of the seismic input, which is based on information about the historical seismicity and seismogenic faults. The second element is the computation of the seismic impact on the building stock and infrastructure in the region considered. Information on urban-scale vulnerability was collected and a geographic information system was used to organize the data relating to buildings and network systems (e. g., typologies, schools, strategic structures, lifelines). The central idea underlying the definition of the Disruption Index is the identification and evaluation of the impacts on a target community, considering the physical elements that contribute most to the severe disruption. The results of this study are therefore very useful for earthquake preparedness planning and for the development of strategies to minimize the risks from earthquakes. This study is a product of the European “Urban Disaster Prevention Strategies using Macroseismic Fields and Fault Sources” project (UPStrat-MAFA European project 2013).PublishedTorino, Italy3T. Pericolosità sismica e contributo alla definizione del rischioope

On assessing importance of components in dysfunction urban systems given an earthquake: the case of Mt. Etna region

Mt Etna region (Sicily, Italy) is one of the test areas studied in the European Project “Urban disaster Prevention Strategies using MAcroseismic fields and FAult sources” ( UPStrat-MAFA) to which the methodology of Disruption Index (hereafter DI), recently developed to evaluate the dysfunction of urban systems caused by earthquakes (Ferreira et al., 2014), has been applied on a trial basis

Seismic Risk Evaluation

This paper reports the main results of the EC-Project SERGISAI. The project developed a computer prototype where a methodology for seismic risk assessment has been implemented. Standard procedural codes, Geographic Information Systems and Artificial Intelligence Techniques compose the prototype, which permits a seismic risk assessment to be carried out through the necessary steps. Risk is expressed in terms of expected damage, given by the combination of hazard and vulnerability. Two parallel paths have been followed with respect to the hazard factor: the probabilistic and the deterministic approach. The first provides the hazard analysis based on historical data, propagation models, and known seismic sources. The deterministic approach provides the input for scenarios, by selecting a specific ground motion. With respect to the vulnerability factor, several systems have been taken into account apart from buildings, which are usually considered in this type of analysis. Defining vulnerability as a measure of how prone a system is to be damaged in the event of an earthquake, an attempt has been made to move from the assessment of individual objects to the evaluation of the performance of urban and regional areas. Another step towards an approach which can better serve civil protection and land use planning agencies has been made by adapting the analysis to the following geographical levels: local, sub-regional and regional. Both the hazard and the vulnerability factors have been treated in the most suitable way for each one, in terms of level of detail, kind of parameters and units of measure. In this paper are shown some results obtained in two test areas: Toscana in Italy, for the regional level, the Garfagnana sub-area in Toscana, for the sub-regional level, and a part of the city of Barcelona, Spain, for the local level.Published257–2675T. Sismologia, geofisica e geologia per l'ingegneria sismicaJCR Journa

Bayesian Analysis of a Probability Distribution for the Regional Intensity Attenuation

The regional intensity attenuation and its variation as a function of the distance and earthquake size is still a critical problem in the seismic hazard evaluations. We present a method that allows us to incorporate additional information of the historical earthquake felt reports in the probability estimation of the regional intensity attenuation. The approach is based on two ideas: a) standard intensity versus epicentral distance relationships constituite an unnecessary filter between observations and estimates; b) the intensity decay process is affected by many, not well known elements (physical parameters of the source, propagation path effects, building conditions, semi-qualitative character of macroseismic scales, etc.) and hence it should be treated as a random variable like the macroseismic intensity. We assume that the decay, defined on the set {0, 1,...,Io}, follows a binomial distribution with parameters (Io , p); p depends on the distance from the epicenter and is related to the probability of having null decay at that distance. According to the Bayesian approach this p parameter is, in its turn, a Beta random variable. The observations related to earthquakes with epicenter outside the area in exam, but belonging to homogeneous zones, are used as prior knowledge on the phenomenon, while the data points of the events inside the area are used to update the estimates through the posterior means of the quantities in interest. A detailed description of this methodology is given by applying it to the Umbria-Marche area, Central Italy. The data sets examined are the macroseismic intensity database DOM4.1 and the zonation ZS.4, both compiled by the Italian Group for the Defence against Earthquakes (GNDT). Moreover the method is validated comparing the observated and the estimated intensity data points of the Camerino (28/07/1799) and of the Colfiorito (26/09/1997) earthquake

How to estimate anisotropic attenuation exploiting prior isotropic knowledge

The pattern of the highest intensities in macroseismic fields of volcanic areas is strongly anisotropic because of the linear extension of the fault. In the isotropic approach to the estimation of the probability distribution of the site intensity the analysis starts considering the sites inside circular bins, with fixed width, around the epicentre. To consider the source effect it seems natural to shift epicentre to the rupture length and circular bins to elliptical ones. To exploit prior information on the attenuation trend in Italian seismological and volcanic areas we transform the plane so that an ellipse becomes a circle with diameter equal to its minor axis, and then estimate the probability distribution of the site intensity applying the method proposed in Zonno et al. (2009) to the transformed data points

Application of artificial intelligence techniques in seismology and engineering seismology

In the field of risk evaluation and seismic hazard assessment, it is necessary to codify a great quantity of aspects of the so called knowledge and to supply an intelligent support for the not-well-defined problems (data uncertainty, lack of rigorous solution algorithms). The main feature of an expert system is to emulate effectively the behaviour of a human expert in a particular and defined field, enabling the final user to improve its decisional process and giving access to him to a knowledge base otherwise not clearly codified. From these general considerations the intention came to develop the prototype CZAR (Classificatore Zone A Rischio) that is an expert system reproducing the Italian seismic classification based on the definition of Seismic Hazard given by Progetto Finalizzato Geodinamica (PFG) of the Consiglio Nazionale delle Ricerche (CNR). The expert system built up on the commercial shell Nexpert Object is working on a personal computer through a graphic interface developed with the Graphical User Interface (GUI) of Window 3.0. This user friendly interface makes possible the choice of different procedures to estimate the hazard parameters and also allows the activation of the classification inferential process. The influence of different assumptions and strategies has been evaluated by a mathematical algorithm suggested by the general structure of the Bayes’ theorem. In this paper the prototype of the expert system has been applied to the data relating to Toscana region (central Italy) and the interactive evaluation of the maps furnishes a relative measure for discrepancies on seismic classification in the 2nd seismic category.Published153-1735T. Sismologia, geofisica e geologia per l'ingegneria sismic

A different intensity recording for reducing the uncertainty in its assessment: An application to the completeness analysis of earthquake catalogues

The purpose of this paper is to emphasize the consequences of the ordinal and qualitative nature of seismic intensity regarding its recording. The classical way of recording by an integer value implies that on many occasions it can be difficult to associate only one intensity degree to an event. Therefore, we propose to record the intensity in a new way so that the expert is no longer restricted to indicating only one value, but can express his belief that the considered event belongs to any one of the intensity classes in the scale. Following this approach, as an example, we study the completeness of the Sannio-Matese catalogue and show how the degree of completeness changes according to the degree of uncertainty in intensity assessment.Published47-586T. Studi di pericolosità sismica e da maremotoJCR Journa