Seismic vulnerability assessment - Prometeo

Seismic vulnerability assessment: from physical to systemic and organizational aspects Silvia Cozzi, Scira Menoni, Floriana Pergalani, Vincenzo Petrini Introduction The Eighties were crucial for the beginning and the subsequent development of research and studies to provide Italian public administrations with a coherent methodology to assess seismic risk. As usual, unfortunately, the political input on the scientific community came as a consequence of the severe earthquakes that hit in 1976 the Northern Friuli region (with more than 965 deaths, more than 2000 injured and 90.000 left homeless) and the Irpinia area across the Southern Campania and Basilicata regions (with 441 deaths, more than 50.000 injured and 150.000 left homeless). The first important consequence of those two earthquakes on Italian prevention policies was the decision to issue an earthquake hazard map for the whole nation, based mainly on historic evidence of past earthquakes. Instead of continuing the usual policy of considering seismic only those areas where a severe earthquake has just occurred, a large study was initiated to define areas where earthquakes could be expected, even though nothing has happened in the recent years. As time intervals increase also in relation to ground motion severity (resulting from a larger amount of elastic energy that had time to build up in active faults), it became clear that historic records of at least a thousand years should be made available to define those active areas. The large research that was produced in the late Seventies made it possible to develop the historic seismic catalogue and t approve the first seismic classification of Itlay in 1984. The Friuli and Irpinia earthquake had also another important consequence: for the first time politians and decision-makers recognised that the high level of damage could not be explained on the basis of severe ground motion only, other aspects had to be taken into account as well, pertaining to the response capacity of buildings, settlements and organisations. The same year of the Friuli earthquake, 1976, the Progetto Finalizzato Geodinamica (a project to study geodynamic processes in order to characterize Italian seismicity) was set by the CNR (National Research Council), constituting an important tool linking the scientific community to the Italian Parliament; in 1982 Giuseppe Grandori presented the finding of a pioneering study, aimed at comparing the cost of damage to be sustained in Italy as a consequence of an earthquake similar to those that had been just experienced and the cost of retrofitting and reinforcing existing masonry buildings. It became clear that the law 64 passed some years earlier was not going to affect substantially the vulnerability of the majority of Italian towns and villages, most of which built long before 1974. Further studies and applications demonstrated that in the face of Italian seismicity, which can be considered moderately high (but not comparable to Japan or California), good maintenance, good building practices could save buildings from failure and collapse. The 1976 earthquake opened the season of comprehensive surveys on existing buildings, to assess the main parameters that explained their behavior under the dynamic stress provoked by earthquakes. In particular, the databank of the Gruppo Nazionale Difesa Terremoti was initiated using the data coming from the 1976 damage assessment, giving the possibility for the first time to estimate correlations between damage and vulnerability. In the interpretation that was given by Italian seismic engineers like Petrini, Grandori, Guagenti Grandori and Benedetti and which is presented in the following paragraphs, vulnerability is a measure of how prone is a system to be damaged as a consequence of an external input, represented in this case by the ground shaking. This interpretation is derived from a report issued by the Undro (United Nations Disaster Relief Office1979), the United Nation office for disaster prevention at that time, resulting from a workshop to which the most important experts in the “disaster community” participated. In the Italian applications that will be discussed, according to the authors mentioned above, the concept of vulnerability has been increasingly gaining autonomy from that of damage: vulnerability is considered as an intrinsic fragility of the system and not as potential damage. The latter is 1

considered to be the unit of measure of risk, thus resulting from the combination of hazard and vulnerability of exposed systems. The presence of large and important historic centres in Italy explains the importance granted to vulnerability studies also by governments and public administrations. In fact, historic centres are characterized not only by important monuments but also by the wide number of traditional, minor masonry and stone buildings, constituting the “environment” of works of art and a unique feature of the Italian landscape. In the years since the first experiences mentioned above until now, vulnerability studies have developed along different directions. As for buildings, forms to examine the most relevant features that make a building resistant or fragile have been set by the GNDT (they will be discussed in detail in the next sections). The data collected by filling forms during a survey, have been used to create a large database and permitted the development of more extensive and less time consuming surveys, ranging from sample techniques to the use of “poor”data derived from the national census on population and housing. The vulnerability concept has been then applied also to other urban systems, ranging from public facilities to lifelines, as discussed later on. In those cases, vulnerability was not intended only in physical terms, but also systemic and organisational. What is at stake is not only the physical capacity of a system to resist an earthquake, but also the capacity to continue functioning despite a given level of physical damage that may have occurred as a consequence of shaking. Public facilities such as hospitals and firemen departments, or lifelines are required to function even if partially hit by an earthquake. This capacity does not stem only from physical characteristics, but depends also on organisational and functionals factors, deriving from the systemic complex links that exist especially among urban and regional systems and between the latter and the organisations in charge of them. Currently the research in this field comprises among its goals the extension of the vulnerability concept and vulnerability analyses to other hazards, natural (such as hydrogeological) and technological (vulnerability and exposure assessments are required in order to decide safety distances between hazardous plants and settlements according to the EU Seveso Directive III). What is peculiar and interesting in this Italian 30 years long experience is that it was not left confined to academia institutions; instead it entered in the activities of at least some public administrations, as the examples provided in the text clearly show. Vulnerability assessments became the basis for some political decisions, for assigning funds for urban plans, for assessing the feasibility of urban master plans, as they became part of geological reports supporting land use planning decisions.

1. Definition of risk The term “Risk” defines the entity of damages expected in an area due to future events and it comes from the convolution between hazard, vulnerability and exposure (Fig. 1.1).

Hazard

Vulnerability

Risk

Fig. 1.1 – Definition of Risk as a convolution between hazard and vulnerability 2

RISK = Hazard * Vulnerability * Exposure In this case, the considered hazard is the occurrence of an earthquake, and the vulnerability is represented by the response of the different involved systems (buildings, infrastructure networks, punctual work, etc.) to the seismic event and also people exposed to the effects that this event may produce.

2. Definition of hazard

Seismic hazard can be assessed by following either a probabilistic or a deterministic approach. The first approach considers the probability that in a specific site and in a predefined time-window a certain hazard severity may be reached. It permits to obtain foresights about future events in a given area, estimating the probability of having an event stronger than an established severity in a given time period, making use of probabilistic analysis of past events and of the available knowledge regarding existing faults and other seismogenetic parameters. The result is a distribution function in the site and the determination of possible hazard indicators. In the deterministic approach an individual event and its propagation in the surrounding areas (hazard scenario) is selected. In this case, a level of ground motion in a given area must be determined. Different data sets are considered to investigate how the phenomena propagates far from the epicentre according to attenuation laws, providing as a result the variation of severity at given distances from the epicenter. To do that, knowledge of structural geology and historical seismic data must be used. In Italy the following basic data are available: 1 Historical recorded events catalogue. For every recorded event it is possible to find out information including the indicators of epicentral severity: epicentral intensity and magnitude. 2 Source zones. Those are areas that can be considered geologically, structurally and kinematically homogenous. A seismic zone is defined through the probabilistic distribution of epicentral intensities. 3 Attenuation model. For assessing the hazard it is necessary to know, beside the localization and the epicentral severity, how the phenomenon propagates from the epicentre and how correlated severity parameters change accordingly. Intensity attenuation. Using the epicentral severity as indicator, the result of the attenuation laws is still an intensity value. Magnitude attenuation. These models use as severity indicator the magnitude value. Once this basic seismic input is estimated in each location, another important step must be fulfilled in order to consider local seismic effects. The latter can modify, even substantially, the basic seismic input: particular geological and morphological conditions characterizing a specific area (i. e. morphological irregularity, deposits, landslides, etc.) may amplify the ground motion. For areas prone to produce local effects (and then potentially dangerous) soil response to different shock levels must be investigated. The latter can be distinguished in: -

instability effects: collapses or movement of soil or rock blocks that can be triggered by the seismic input;

-

site effects: represented by the interaction of seismic waves with particular local condition, that can modify the characteristics of surface seismic response compared with the shaking in the bedrock. Surface and buried morphologies, particular geological and stratigraphical soil characteristics can generate local amplifications of seismic waves transmitted by terrain and by resonance phenomenon. 3

3. Definition of vulnerability

This term intends to ascertain to what extent an object is prone to be damaged in case of earthquake occurrence. The concept of vulnerability is closely linked to that of “exposure”, indicating the number of exposed people and the quantity and value of threatened goods. There is a risk only if there are objects that may be damaged or people who may be involved in the area where the event occurs. It is then important to analyse the area and verify which and how many kinds of objects and people are exposed. Secondly it is important to assess how vulnerable they are. The vulnerability assessment can change depending on different typology of elements to consider. For example, the most direct process to establish the built environment vulnerability is to make use of vulnerability investigations. It is clearly very difficult to investigate the whole built patrimony for large areas, but it is possible to obtain approximate evaluations. While point-shaped structures, such as bridges, tunnels or supporting works, it is possible to draw up survey cards articulated in different sections regarding specific characteristics of the considered object, the vulnerability assessment for complex works, such as lifelines, is particularly delicate. In fact, network infrastructures (like streets, railways, waterworks, gas network, electric network, and so on) are complex structures composed by pipes, joints and plants, sometimes strongly, sometimes loosely linked one to the other. So, it is important to study their vulnerability not only from a physical point of view but also considering systemic and spatial aspects. The following sections will illustrate different examples of current methods used to assess vulnerability for any typology of elements at risk and most common damage potentials, taken from Italian applications. 4. Vulnerability assessment of residential buildings developed in Italy Residential buildings have been the first urban system that has been dealth with by seismic engineers in Italy. The reasons are quite simple: the first relates to the fact that the highest level of damages and the largest number of victims occurred in vulnerable houses in every earthquake experienced by Italy in the post-war period, and particularly during the Friuli and the Irpinia earthquakes. The second reason is that residential buildings adopt a rather typical structure and are therefore easier to classify than special buildings, such as churches (presenting the highest possible variation in terms of morphological, typological and construction characteristics), theaters, factories, etc. Vulnerability assessments have been developed for both reinforced concrete and masonry buildings, the latter representing the majority of the whole built patrimony, practically in all Italian regions. In the following paragraph the method that has been set over thirty years of continuous research and field experience will be described. Then it will be discussed how the method was adapted to be used for large scale surveys, at an urban and even national scale. Finally an interesting project carried out by the Italian Ministry of Labour in conjunction with several national, regional and local authorities will be shown: it consists in the application of the buildings vulnerability assessment method to create a vulnerability census of public facilities in all Southern regions. 4.1. 1° level forms to analyse buildings For the following steps, consisting of the seismic vulnerability survey for residential buildings, 1° and 2° level forms are used. The survey card consists of three pages: the first and the second pages form provide for the first level card, that includes general information about buildings location, geometry and typology. The

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third page contains information about the vulnerability of the considered building and therefore is considered a second level card. The first level card consists in the following 8 sections: 1.1. data about the card (building identification key, municipality, card, team, date); 1.2. building location (aggregate, building, toponymy, town planning bonds); 1.3. metric data (surfaces, landing hights, maximum and minimum out of round highs); 1.4. use (kinds of use, state, property, users); 1.5. building age (typologies and classes of age); 1.6. state of the trimmings; 1.7. structural typology (vertical, horizontal, staircase, roofing); 4.2. Vulnerability assessment The second level allows to assess vulnerability by using representative data about buildings propensity to be damaged by a seismic event. In particular some factors accounts for the behaviour of the elements, structural or not, some others of the behaviour of the whole building complex. 2.1. sort and organization of resistant system; 2.2. quality of the resistant system; 2.3. conventional resistance; 2.4. position of the building and of the foundations; 2.5. ceilings; 2.6. planimetric configuration; 2.7. elevation configuration; 2.8. maximum distance between brickworks; 2.9. roofing; 2.10. non structural elements; 2.11. general conditions/present state; In order to obtain a numerical index, each parameter may be assigned to one of the four classes that have been set, distinguisching four vulnerability levels, from A, the best one, that is the least vulnerable to D, the worst, that is the most vulnerable. Besides those four classes, with respect of the “vulnerability” or “resistance” quality of the building with resepct to each parameter, the latter has been assigned also a weight, representing the importance of the parameter within the assessment procedure. This means for example, that the organisation of the resistant system, as well as general maintenance conditions are very important to determine the resistance capacity of a building, and therefore assigned weight 1. Other parameters, which are of minor importance, are assigned lower weights, meaning they will count less in the final assessment. The vulnerability score of each building is then obtained through a weighed sum, in which each parameter is assigned to a class (A,B,C,D) translated into a score (as it can be seen in the attached table) and multiplied by the weight representing its importance. Obviously, this methodology is useful especially to set up comparisons between buildings and to assess the position of each building with respect to a maximum and a minimum level of vulnerability. In other words the vulnerability final score does not have any intrinsic meaning per se, but only with reference to a vulnerability scale, the specific scores being rather arbitrary and without any cardinal value. The obtained vulnerability index constitutes a conventional measurement of the propensity to damage that does not coincide with the expected damage. In order to validate the method, it is of course necessary to find a correlation between damage level (surveyed after an earthquake), the quality of the building and the parameter used to measure the earthquake severity (see figure 4.1, related to the Friuli and Irpinia earthquakes). The definition of this correlation presents some difficulties: in fact, theory models available to evaluate seismic damage levels require very complex and expansive detailed analysis of every single building. Those 5

models are, therefore, incompatible with the need of rapid evaluation of the building heritage at regional level. So, in this case, relations based on statistical elaboration are used; they relate a damage index for different values of the vulnerability index considering different level of peak ground accelerations (Pga).

Fig. 4.1 – Fragility curves 4.3. From the assessment of individual buildings to large scale evaluations The method that has just been described in detail cannot be applied to large areas, neither to the entire territory of a region or a country nor to a large town. What is needed therefore is a simplified method, or a method that can provide a result in shorter time, without surveying each individual building. This can be done through statistical approaches: of course what is gained in terms of covered quantities and extension is lost in terms of accuracy and results reliability. Nevertheless the result may be meaningful for several urban planning and long term national programs. As for urban areas, a sampling method has been proposed and applied: it consists in dividing the built patrimony in sub-sets characterized differently in terms of building material, period of construction, morphology, typology, etc. A sample (or more samples) of each sub-set is then evaluated using the procedure discussed in the previous paragraphs and then the result is extended to the entire subset, using common statistical methods. This sampling method has been followed to evaluate the residential buildings vulnerability and expected damage in the seismic areas of Lombardia region (see Regione lombardia, 1996). The second application was even more general, as all the Italian municipalities have been assessed in terms of their seismic vulnerability. In this case, “poor data” taken from the census has been used, extrapolating the few parameters that may be interpreted as “vulnerability symptoms”, that is building age, type of construction and level of maintenance. The resulting map is obviously not accurate, but it provides an interesting overview of the entire nation, suggesting expenditure direction to state agencies in charge of risk prevention (see Bernardini, 2000). 4.4 Vulnerability database of public, strategic and special buildings in Southern Italy An interesting application of the methodology that has been discussed previously has been run in Southern Italy to create a vulnerability database of all public and strategic facilities in the context of the so called “Lavori Socialmente Utili Project” (Social Useful Work Project). This project was aimed at funding projects giving the opportunity to jobless people to access a specialization and a real work experience in administrations or fields where personnel is missing. In 1995, with the Order in Council n. 323 of 14th June, the Civil Protection State Department in partnership with the Labour Ministry decided to start a project in the field of seismic vulnerability surveys.

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The project was aimed at analysing the vulnerability degree of public and strategic buildings in Southern areas prone to seismic risk, giving an opportunity to employ architects, engineers and graduated students from technical high schools. The objectives set from the Project were essentially two: 1. seismic vulnerability survey. It permits to obtain seismic vulnerability lists, useful for Local Administrations to: 1.2 draw up seismic risk maps and civil protection plans for the assessed areas; 2.2 estimate expected damages. 2. technician training in seismic prevention matter, in order to obtain: 2.1 the training of a large number of technical experts who will be able to intervene in case of need (for example after an earthquake to evaluate the condition of affected buildings); 2.2 dissemination of available seismic risk assessment methodologies, not only among technical experts, but also among different involved administrations. First results consist in the complete vulnerability census of the public building heritage in seven regions of the Southern Italy: Abruzzo , Molise, Campania, Basilicata, Calabria, Puglia e Sicilia. Some adjustments were made to make the GNDT method fit for the purpose of this particular project. In particular, it was required to fill a pre-form before actually using the two levels forms that have been described in the previous sections (4.1; 4.2 and 4.3 sections). The Pre-form is a preliminary instrument used to take a census of every public buildings in each municipality. This card is arranged in two parts. In the first one general information about the municipality and the agency that is compiling the form are collected, while the second part is composed of nine parts including: 1. identification of the complex; 2. typological elements; 3. building use; 4. previous seismic vulnerability evaluations; 5. time of curse; 6. cognitive elements of the complex; 7. historical or architectural features, or particular environmental value; 8. town planning situation; 9. building interventions. The professionals involved in the project attended an initial course and a practical training in the field tutored by civil protection staff. The following arguments were taught: civil protection, seismic risk, seismology and seismic hazard, structural engineering, labour law and other legal aspects. Special attention was devoted to the seismic risk assessment methodology to be used and to the forms to be completed by the attendants. In the field surveys other organisations participated as well, in particular some municipal technical departments, the National Engineers Association, Regional and provincial officers and the Carabinieri ( a special police body of the Army). The evaluation of the seismic risk for public and strategic buildings is not the only product arisen from the project. In fact, there are several intermediate products, realized during the data sets transformation, aggregation and elaboration, that will constitute a precious base of knowledge for future researches and applications. The most relevant are: ¾ computerized database, complete and easily accessible; ¾ statistic information about territorial distribution of public buildings for homogeneous vulnerability zones; ¾ formulation of hypothesis of technical and economical intervention in order to obtain an optimal seismic risk mitigation. 7

Region

Number Number of surveyed municipalities buildings

Abruzzo Basilicata Calabria Campagna Molise Puglia Sicilia

305 131 409 551 136 258 390

Fig. 4.2 – Territorial area involved in the vulnerability survey for public buildings

REGION Abruzzo

2.536 3.242 10.083 13.388 2.661 1.829 7.558

Tab. 4.1 – Data about the municipalities involved and the buildings surveyed by theProject

Number Persons how Computer Engeneers Architects Surveyors of works in TOT. Scientists teams administrations 34

7

43

33

5

5

93

25

16

8

47

6

6

83

83

33

91

108

16

15

263

94

16

32

202

24

23

297

15

3

7

34

5

5

54

43

10

18

76

4

7

115

Sicilia

51

38

34

62

14

13

161

Tot.

345

123

233

562

74

74

1.066

Basilicata Calabria Campagna Molise Puglia

of

Tab. 4.2 – Data about professional involved in the Project for each Region

4.5. Summary of the case studies In the section the method to carry out seismic vulnerability assessments on residential buildings has been described. The first system that was considered by the GNDT in developing the vulnerability assessment tool were residential houses, because they present a homogeneous and typological standard at least in a given geographical region. Extended applications of the method, to assess large scale areas were shortly discussed, as well as an interesting project, carried out in coordination with the Labour Ministry to employ technical experts, such as architects and engineers to survey all public buildings in Southern Italy. While this experience is valuable from different points of view, as it permitted to train experts to be called in case of need to help in buildings surveys after earthquakes and to collect relevant information 8

regarding public facilities exposed to seismic risk, it still shows some limitations. The most relevant being the lack of any reference to what will be called in the lifelines example, systemic, functional and organisational vulnerabilities, which clearly play a significant role in this particular type of urban systems. 5. Vulnerability assessment of historic centres as part of urban restoration project A rather pilot experience in the field of urban vulnerability assessment has been promoted by the Emilia Romagna Region in the Eighties. It started from a regional law (RL 35/1984) requiring that specific seismic vulnerability assessments be carried out as part of the feasibility study accompanying any urban restoration project, in the context of the Regional Development Program 1986/1888. According to the Emilia Romagna interpretation, each urban restoration plan should consist of two parts: a feasibility study and the actual restoration project. The feasibility study should: - verify how the area will be transformed with respect to predetermined preservation criteria; - specify the rules supporting the decision making process, valuing the participation of interested parties and stakeholders besides the public administration; - define procedures and tools to coordinate public and private resources; - establish the implementation phases of the interventions and their management. Therefore, through this instrument/tool it is possible to outline a “goal-oriented approach”, represented by a clear program establishing planning, financial and implementation aspects. The feasibility phase is therefore particularly suitable to highlight all the potential problems to be faced, including seismic risk. A detailed study of buildings and urban vulnerability was required. Guidelines were produced to help professionals in carrying out such an assessment; the guidelines included a simplified version of the GNDT forms for buildings and some interesting new parameters regarding other urban elements that have never been considered until then, such as urban morphology and patterns, characteristics of access ways, including pavement, width, inclination, etc. The idea was to identify urban vulnerabilities not related only to buildings but to other important parts and systems. Finally, the urban restoration project was aimed at describing and prescribing how the historic area should have been preserved, using which techniques, materials, etc. A particularly important point was the part of the project suggesting how the restored centre could be reintegrated into the larger urban and community life. In the following paragraph an example of such a restoration plan will be illustrated. 5.1. The restoration plan of Castel del Rio’s old town centre (Province of Bologna) The old town centre of Castel del Rio is situated in the Emilia Romagna Region, in Province of Bologna and its landscape is typical of the Tosco-Romagnolo Appennine, characterized by middleheight range and by wide woodlands (the predominant species are chestnut and beech), that cover more than an half of the municipality territory. Among the significant events that affected Castel del Rio it is possible to remind the Mugello earthquakes occurred in 1542 and in 1722. The urban pattern was significantly changed by the new state road “Montanara”, started in 1829 and finished in 1882. In the period after the Second World War, Castel del Rio was developed at the west side of the old town centre, of Middle Ages origin, up to the hill where stands the old fortress ruins and where no further development is possible. The building types present in Castel del Rio are included in the Apennine context of the so-called “masonry buildings”. The basic building in this area is suited for the morphological characteristics of the terrain and follows two main typologies: 9

1. slope houses, with loggias in the outside; 2. row of houses. This second building type was the object of the urban restoration plan. It is possible to notice that they have a quite old dating (XV and XVI century), in particular for the building in the old town centre square. The following building typologies have been analysed in detail: - bearing walls, realized in sandstone according to two criteria: dry stone walls or masonry tied up with plaster mortar; - floor slabs, made with chestnut-tree wood; - roofing, made of wood rafter. Three restoration zones have been defined in the central part of the old town centre (Fig 5.1). 5.2. Significant and innovative aspects of the urban restoration plan The most significant aspects of the plan concerns the application of the Regional Law 35/1984, following the guide lines for historic centres restoration in seismic areas. In the feasibility study therefore the following elements have been considered, looking at the overall capacity to resist earthquakes: the geometrical and structural survey for all the buildings included in the plan; the analysis of materials characteristics, both for vertical structures and for floors and roofing; the presence of different kind of connections; structural and material deterioration; to the structural survey is placed side by side the “critical survey”, consisting of the reading of the transformations occurred over time in order to understand the development of buildings and blocks. Seismic vulnerability has been therefore considered not only statically but also in terms of its historic formation (for example as a result of interventions on already existing buildings or repair after earthquakes). Particularly vulnerable features have been recognised for example: at the extremity of the blocks there are buildings having strong morphological unevenness; in the central part of the section there are problem of widespread structural irregularity, such as walls of different material and thickness put one close the other and discontinuity in bearing walls; the zone of the section to the east of the central square (that comprise the church), presents distortions in the masonries that overlook the river that runs along the city. In order to respond to the structural weaknesses that have been summarized above, the following interventions were forecasted: correcting the irregularities using the typical building materials; prescription of building uses compatible with the historical features and the vulnerability of the various buildings; guaranteeing the preservation of local building characters in seismic retrofitting works. In particular, the following prescriptions were adopted: 1. for boundary walls, by eliminating possible instabilities and reducing possible weak points; 2. for floor slabs, by building good connections with vertical structures; 3. for arches and vaults, by eliminating horizontal drifts. From an operational point of view, the plan singles out the “minimum unit of building intervention”(composed by one or more buildings and their immediate surroundings), that is the direct building intervention unit, especially in case of substitutions, insertions or shifting of structural elements. The urban restoration plan provides, at last, street furniture interventions, such as the re-paving of the central square and the carrying out of a pedestrian course crossing the old town centre. The attention to pavement and accessibility is driven by concerns in the case of emergency operations.

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5.3. Summary of the case-study The experience of the Emilia Romagna Region is particularly valuable as it opens for the first time to wider vulnerability concerns, aimed not only at buildings vulnerability assessments but also to other features of the urban environment. Furthermore it is an interesting example of how a methodological procedure that has been developed in academia could enter into the ordinary practice of a public administration. Last but not lest, the procedure was aimed at integrating seismic risk concerns into a current tool (the feasibility study) used for planning purposes to encourage the preservation of the rich historic heritage of Italy, made not only of individual works of arts but also of traditional masonry buildings.

Fig. 5.1 – Castel del Rio old town centre and urban restoration plan area

6. Lombardia Region: a systemic approach to assess lifelines earthquake vulnerability In 1999 the Lombardia regional administration has commissioned a study to earthquakes, to develop a model to evaluate lifelines seismic vulnerability. The assessment tool that was developed has been applied in Lombardia Region, providing as a final output recommendation for prioritizing and taking actions to reduce the potential of magnified effects as a consequence of lifelines interruption in earthquakes aftermath. This work has been divided in two parts: the first aiming at building a conceptual framework and testing it in the most seismic areas of the region, the second to produce complete earthquake scenarios including lifelines disruption. 6.1. Lifelines vulnerability assessment methodology Lifelines are made of multiple components—linear pipes, substations, control centers, power generating systems—obeying to highly hierarchical functions and it is therefore impossible to 11

isolate single parts and analyse them separately one from the other. They depend from each other in such a manner that inter- and intra- dependency have been recognized as one of their most prominent characteristic. Finally lifelines are connected with the external environment: the latter can be viewed as a source of induced damage (as in the case of collapsing buildings or landslides), but also as end-user of utilities like water, electricity, gas, and communication. For all these reasons, specific approaches are required to assess lifelines seismic vulnerability, in order to account for some of their particular features. The notion of systemic vulnerability is the underlying frame of the proposed evaluation method: what can be measured is how prone is a system to damage or failure not only as a consequence of some kind of physical damage occurring to one of its components, but also as the indirect effect of some physical, functional, or organizational failure suffered by other systems. In this regard, as lifelines are highly hierarchical, the consequence of failure in crucial components or parts of the system has been devoted higher attention in the framework. The model accounts also for lifelines inter-dependency, which can be either physical (lines laid in the same corridor running below roads) or functional (for example electrical power is vital for many other utilities: communication networks, control devices, water pumping stations, etc.). Urban and regional systems depend on lifelines at different degrees, according to their specific needs as service users and also depending upon the considered disaster phase. This is the reason why distinct assessments matrices have been developed addressing separately the emergency and the reconstruction periods. While in the first minimal lifelines performance is crucial to guarantee victims assistance and rescue activities, return to normalcy at acceptable costs becomes the new priority in the reconstruction stage. In each matrix, thresholds of good and bad performance as well as weights expressing parameters importance have been set according to the different priorities identified in the two phases. The general framework to assess lifelines vulnerability in the emergency has been reported in Table 6.1: functional, organizational and physical vulnerabilities are grouped, respectively, in the first, second, and third columns. Functional factors explain lifelines malfunctioning due to a variety of reasons, many of which are not physical. Each lifeline is a hierarchical system: if crucial nodes fail, the service they provide in normal time will inevitably cut many customers off. Those nodes are, for instance, stations transforming high into medium or into low gas pressures, energy power stations, water reservoirs, etc. Organizational factors that are considered in Table 6.1 may consistently hamper search and rescue activities. Communication systems provide an enlightening example in this regard: the most frequent problem encountered in the first hours following the impact of a disaster is lines overloading. Another important organizational parameter to assess coordination among those involved in emergency management is the number of companies managing lifelines or even the same lifeline in a given area. A few big firms are able to control interactions emerging among their lifelines and others and are therefore more likely to sign protocols and mutual agreements for joining operations whenever needed. The rows in Table 6.1 are grouped in three main blocks: in the first, factors related to lifelines performance are considered, in the second siting situations are examined. The last group of rows indicates how vulnerable urban and regional systems (other than lifelines) are to the interruption of services like electricity, water, gas, and communication. The form to assess lifelines vulnerability during reconstruction contains those elements that are more relevant to recovery. Physical vulnerability is not considered any more, as ruptures are supposed to have already occurred once emergency is over, while functional and organizational aspects still remain important. This time, however, the focus of the assessment concerns inter- and intra-dependency that may hamper quick recovery. In organizational terms, for instance, coordination with public administrations and with institutions in charge of financial aid and support for reconstruction becomes as crucial as the coordination among lifelines managing companies. 12

The vulnerability assessment procedure requires a number of steps to be followed in order to obtain the final result, consisting of a normalized score assigned to each lifeline and of an evaluation of other urban systems vulnerability to lifelines disruption. Both assessments should be carried out for the emergency and the reconstruction phases. The above illustrated table 6.1 shows the form to assess lifelines seismic vulnerability in emergency phase, while a very similar survey path has been developed related to the reconstruction phase. Most of the parameters in this case aim at forecasting the time needed for temporary or final repairs and for establishing efficient cooperation protocols among companies distributing water locally and regionally, as well as with other lifelines managing companies, public administration sectors, etc. For each parameter included in the matrices, at least two or more classes of roughly good or bad present conditions have been established, on the basis of literature and post-earthquakes reports, and the most critical class has been identified. The evaluation step of the developed procedure consists of a weighed sum of factors providing as a final result a vulnerability score. In order to carry out this procedure, the elements surveyed in the analytical forms have been split in two parts, the first considering the performance and siting vulnerability of each lifeline, the second aimed at assessing the degree of other urban and regional systems vulnerability to utilities interruption. Both forms have been developed for the emergency and the reconstruction phases. The application of this procedure provides a vulnerability index to each lifeline. In order to compare lifelines, scores have to be normalized. The normalized scale has been then subdivided into intervals, ranging from low vulnerability intervals (0-0.2), to medium (0.2-0.4), medium-high (0.40.6), high (0.6-0.8), to very high levels (0.8-1.0). Lifelines with a final score comprised in the higher part of the scale, are in a rather critical condition, while lifelines obtaining a low score seem capable of resisting to earthquakes impact. It is then possible to carry out crossed comparisons among lifelines systems and among subareas within the region of interest. 6.1.1. Application of the lifelines vulnerability assessment method to the study area of the Brescia Province The method that has been described insofar was tested, for the emergency phase, in the Brescia Province (Lombardia Region, Italy), where most seismic municipalities of Lombardia are located. This large area has been subdivided in three zones, homogeneous as far as their geographical and urban features are concerned: the conurbation of Brescia and its immediate surroundings, the municipalities in the northern part of the lake coast (Salò), subject to the highest seismic intensities, and the plain areas south to the Garda lake and to Brescia (Desenzano). Following the procedure described in the previous paragraph, as a first step the characteristics of the lifelines systems in the area have been surveyed and the analytical forms filled with the acquired information. Not all the necessary data were available: anyway forms have been filled, though more satisfactorily for water, power and road systems. Secondly, the vulnerability index has been calculated (the results are shown in table 6.2). It has been decided to assign final scores to the entire municipality and not to individual lines, because of lacking or incomplete information as mentioned earlier. Despite this limitation, first results can be considered nevertheless significant and may be used as a decision support tool. Those results show that the most vulnerable area is that of Salò, threatened by several landslides, which may obstruct the only main road and the networks running beneath. The vulnerability assessment of the urban and regional systems to lifelines failure has been also performed, confirming that the Salò area is the most critical also as far as facilities needed for emergency operations are concerned. In the whole province, water, sewage, and gas systems are the most vulnerable, confirming what has been reported in past earthquakes.

13

Tab. 6.1 - Form to assess lifelines seismic vulnerability in emergency phase. FUNCT10NAL

PERFORMANCE

ORGANIZATIONAL

Induced by other systems

FUN P 1

Dependence on other systems

ORG P 1

Inter agencies cooperation

PHY P 1

Physical vulnerability of systems which lifelines are physically connected

Inter-systemic lifelines dependence

FUN P 2

Dependence on other lifelines

ORG P 2

Cooperation among lifelines companies

PHY P 2

Physical vulnerability of lifelines essential for the function of other lifelines

Within an individual line

FUN P 3

Specific lifeline features

ORG P 3

¾

Organization within each company Number of companies for each lifeline Manual controls in case of automatic controls

PHY P 3

Vulnerability of each lifeline component

Coordination between civil protection and companies in charge of roads management Knowledge of alternative accesses Coordination Available personnel, materials and means to be used for urgent operations

PHY S 1

Physical vulnerability of roads

PHY S 2

Physical vulnerability of single component in contact points

PHY R 1

Physical vulnerability of systems other than lifelines necessary during emergences

¾ ¾

Accessibility

FUN S 1

Direct access to broken points

ORG S 1

SITING

¾

¾ ¾ Vulnerability due to the physical contact among lifelines

REGIONAL vulnerability to infrastructures loss

PHYSICAL

Urban and regional systems for emergency operations

FUN S 2

FUN R 1

Other systems FUN R 2

Function depending on physical contact with other physical vulnerable lifelines

Degree of functional dependence of emergency systems on lifelines Degree of functional dependence of other urban systems on lifelines

14

ORG S 2

Coordination among lifelines suppliers

ORG R 1

¾

ORG R 2

Coordination among hospitals, civil protection, police and other agencies ¾ Communication skills to the public Coordination among lifelines suppliers and persons m charge for other systems

PHY R 2

Physical vulnerability of systems other than lifelines

LIFELINE

POINTS Salò Brescia Desen.

NORMLIZED POINTS

Desenzano Brescia Electricity max 98

61

30

Salò

25 0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

Brescia Desenzano Water max 66

47

31,75

0,8

23,5

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

Salò

0,1

0,2

0,3

0,4

0,5

0,6

0,7

Brescia e Desenzano 27

20,25

0,8

51,25

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,1

0,2

0,3

0,4

0,5

Brescia 21

0,9

1

Salò

54,25 0

Communication max 38

1

Salò

Brescia e Desenzano 132

0,9

21 0

Roads max 165

1

27,5 0

Gas max 36

0,9

Salò

Brescia Desenzano 41,5

1

34,75 0

Sewerage max 54

0,9

18

Vulnerability

0,6

0,7

0,8

0,9

1

Salò Desenzano

23 0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

1

0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

1

low

medium

medium-high

high

very high

Tab. 6.2 – Seismic vulnerability index for the analysed Brescia province lifelines in emergency phase.

6.2. Detailed model for estimating damages in seismic scenarios Losses and damages that must be considered with the higher priority during emergencies affect vital systems for search and rescue activities, as it can be seen in the parameters that have been selected in table 6.3. The arrows linking the various boxes represented in each columns show the main relations among objects, subsystems and systems and the kind of damage and failure they may suffer in case of a strong shake. It can be seen that in the first column, besides lifelines systems, buildings and slopes are also represented, though in a diverse (rhomb shaped) boxes. This has been done to account for the induced damage they may provoke to lifelines while collapsing or moving, as it is shown in the third column. In the second one, instead, only the damage directly provoked by the earthquake on lifelines nodes, lines and plants is considered. Starting from the fourth column, systemic aspects are considered: first the kind of malfuncitioning and its maximal duration, derived from past earthquakes reports, must be evaluated. Then affected urban systems vital for managing emergencies, like hospitals and firemen, are identified in the fifth column. Each of those systems depend on lifelines at different degrees, as is shown in the sixth column. Finally, the damage to systems in terms of reduction of their performance is assessed in the last column. It is possible to follow several paths in the framework to assess different types of damage to lifelines, consequences on impacted systems, resulting in several forms of emergency 15

management capacity reduction. In any case the framework draw a model transforming direct physical damage suffered by lifelines and induced damage due to buildings and landslides into systemic failures reverberating through the systems that are more crucial to manage the emergency. Following the conceptual framework provided by Haas et al. (1977), it is assumed that in the reconstruction phase emergency operations are already over and that therefore quick recovery and return to normalcy are looked for. Damage and failure are not measured any more in terms of time delay to emergency operations, but rather as social discomfort and economic costs associated with repairs and with the lack of necessary utilities during several days as it is shown in table 4. The first and the second rows of this framework are very similar to those of the previous one. Starting from the third column things change as parameters expressing economic losses and social discomfort are analyzed. Reconstruction costs depend on the length and number of damaged conducts and pipes and on the availability of material and personnel for repairs. The type of faire and performance reduction is shown in the fourth column, while in the fifth one the impacted urban systems are reported. Economic activities, urban public transport and facilities depend on lifelines at different degrees and may resist without gas, water, electrical power or communication only for a limited period of time without collapsing: this is considered in the sixth column. Social discomfort and economic costs to impacted urban systems are finally represented in the last column. In order to actually run the two frameworks and build the complete event scenario following the time dimension through the emergency and the reconstruction, two main components must be defined in a given area: a seismic deterministic input on one side and the vulnerability of the exposed systems on the other (systems related to lifelines). The combination of the seismic stress with vulnerabilities that are peculiar to a given set of systems and subsystems in a particular area provide the final forecast of damages. As intended here, damages are not only those provoked by seismic waves and ground shaking, but also induced physical damage, such as that resulting from landslides, flooding and fires triggered by the earthquake, as well as other losses and failures, that are referred here as systemic, due to the inter- and intra- dependence of various systems and particularly among urban and regional systems and lifelines utilities. 6.2.1. Development of a complete event scenario to the study area of the Brescia Province It was decided to restrict the scenario building to the Salò area that has been recognised as more vulnerable among those assessed in the previous stage. In order to carry out a complete event scenario in the Salò area, the following steps had to be undergone: - first a deterministic seismic input was selected; - second the vulnerability of roads and water systems was evaluated in order to detect all critical elements and factors (this restriction stems from the fact that only for those systems enough data were available to actually locate the potential damage); - third the vulnerability of urban systems which depend on lifelines for their normal function was appraised. With respect to the emergency stage, the vulnerability of hospitals and fire departments was considered, looking ahead at the reconstruction, the vulnerability of the local economic system was evaluated; - finally the scenario was constructed, combining together the deterministic input, the possible induced hazards and the vulnerability, giving way to a chain of subevents and failures in the area and in its surroundings. To define the seismic input, the higher magnitude regional event (occurred in Veronese), that is magnitude 6.7, has been moved on the epicentral area of Salò in the Brescia Province (Lombardia Region, Italy) Applying the attenuation laws it was possible to obtain the maps of earthquakes in term of peak ground acceleration (Pga) (Figure 6.1) and other characteristic parameters such as Arias intensity, spectral intensity, etc. 16

In order to run a complete scenario, landslides or vulnerable buildings in the area have been identified and represented in two distinct maps. Using a GIS, the latter have been overlaid on the map representing roads and critical roads segments have been identified; finally the previously selected seismic inputs have been applied and induced damages calculated. Landslides displacements greater than 5-6 cm and buildings damage exceeding 60% have been considered the thresholds to induce significant damage to the road system. Direct damage has been estimated as well, by surveying bridges in the study area and by assigning them to a band of fragility curves, corresponding to their structural characteristics and expected resistance capacity to ground shaking. Results show that applying the Salò seismic input, only one bridge may suffer fro damage (>50%). As a consequence of direct and induced damages to the road system, some municipalities north to Salò are isolated and cannot be reached by fire brigades (Figure 6.2). Neither victims can be carried to hospitals if not by helicopter or ships.

GARGNANO

VOBARNO

di G La go

GARDONE RIVIERA

ar da

TOSCOLANO MADERNO

VILLANUOVA ROE` VOLCIANO SUL CLISI

SALO` r 2.75 2.65 2.55

GAVARDO

2.25 2.45 2.35 2.15 2.05 1.85 1.95 1.75 1.65 1.55 1.45 1.35

1.25

1.15

1.05

0.95

0.85

Fig. 6.1 – Pga (m/s2) map of Salò earthquake.

6.3. Summary of the case-study The comprehensive model that has been developed for assessing lifelines seismic vulnerability addresses not only physical factors, but also organizational and functional. A systemic approach has been adopted, to evaluate the consequences of existing interactions linking lifelines to other urban environments when earthquakes occur. A systemic approach has been decided and two different frameworks have been developed both for the emergency and the reconstruction phases, recognizing the different needs and priorities characterising those two post-disaster stages.

17

Tab. 6.3 - Damage evaluation for lifelines in emergency phas Objects

Buildings

Direct physical damage

Physical induced damage

Loss of function and its duration

Collapse

Interruption/ slowing down/ congestion

Roads

Damage to bridges/ roads

Obstruction/ Damage/water indundating roads

Joints/pipes/plants ruptures

Ruptures/conta mination

Hospitals

Fire departments

< 3 months

No service Joints/pipes/plants

Sewerage

Communications

Electricity

Slopes

< 3 months

ruptures

Joints/pipes/plants

Gas

Ruptures

ruptures

Damage to plant

Ruptures/ Water infiltration

Damage to lines, aerials

Damage to plants, lines, transformation station

Landslides

Damage to plants, lines, transformation station

Urban systems degree of dependence on lifelines

Damage to urban systems

R W S G C E

M. (Medium) V.H. (Very high) H (High) M. (Medio) M. (Medio) V.H. (Very high)

Hospitals can’t be used

R W S G C E

V.H. (Very high) V.H. (Very high) L. (low) L. (low) C L. (low)

> 6 months

No service

Water

Hit urban systems

Control room

No service

< 3 months

Difficult to get the line

< 2 weeks

No service

< 2 weeks

18

Police

Dangerous industries

Residential buildings in epicentral area

Lack of information No access

R H (High) W L. (low) S L. (low) G L. (low) C V.H. (Very high) E H (High)

Difficult control over emergency operations

R V.H. (Very high) W L. (low) S L. (low) G L. (low) C H (High) E L. (low)

Lack of information; no access

R M. (Medium) W V.H. (Very high) S L. (low) G M. (Medium) C M. (Medium) E V.H. (Very high) R H (High) W H (High) S H (High) G M. (Medium) C M. (Medium) E M. (Medium)

Induced accidents

No access; difficult to control fires

R= Roads, W= Water, S= Sewerage, G=gas C=Communication, E=Electric power

GARGNANO

TOSCOLANOMADERNO VOBARNO

GARDONERIVIERA

ROE` VOLCIANO

SALO`

Lag o

VILLANUOVA SULCLISI

keys Can’t be reached Can be

m GAVARDO

Fig. 6.2 – Damage scenario of road system: accessibility at municipalities whit hospitals

The assessment procedure leads to a double result: a judgment on the intrinsic quality/fragility of each lifeline system and a judgment on the degree of vulnerability of other urban and regional systems to lifelines failure. It is therefore possible to compare lifelines with respect to their relative vulnerability, to analyse the degree of autonomy/dependency of other systems on lifelines to compare different areas within a larger region, identifying the most critical situations. The model has been constructed in such a way to provide the largest number possible of outputs, in order to open a wide range of alternative options for preventive action either to mitigate the disaster impact in the emergency stage or to bring back the system to normalcy as quickly as possible in the recovery phase. The proposed method and its first application have interesting implications for mitigating earthquakes negative effects due to lifelines malfunction. First results obtained in the seismic municipalities of the Brescia province provide a guideline for addressing successfully emergency management plans as well as for establishing criteria in deciding where and how fast repairs and return to normalcy should be guaranteed. Several issues still remain unattended: many procedures to assess the vulnerability of specific lifelines components have to be developed and more accurate surveys and studies concerning the degree of dependence on lifelines of productive and service activities have to be carried out. 7. Conclusions The methodology that has been described in the previous pages allows to estimate expected damage due to earthquakes in a given area. The expected damage, the unit of measure of risk, results from the combination of hazard and vulenrability of exposed systems, both in probabilistic methods as well as in scenarios, where a deterministic input is provided. In fact, what differentiates probabilistic and deterministic approaches is only the way the hazard is accounted, while probabilistic vulnerability assessments are not available and perhaps impossible to achieve. 19

The chapter focuses on how different vulnerabilities have been measured and assessed, ranging from physical to systemic and organisational vulnerabilities. The examples that have been provided derived partially from experiences that were taken by public administrations with responsibilities in civil protection and risk prevention. The last example, constituted by lifelines vulnerability assessment has been commissioned by a public authority (a department of the Lombardia regional administration) but constitutes a pilot study, that did not imply any effect on current practice. Though, it represents an interesting enlargement of the method to other systems beyond buildings and heavily implies systemic, functional and organisational factors as the core of the vulnerability of complex systems. The last part of the example, describing the complete scenario development, has two goals: on one side to show how vulnerability assessments enter into a damage scenario, that is what is the final use of this kind of assessment; on the other it opens the ground for further development of the method, introducing the concept of chain of losses and failures as part of the response of urban and regional system to any environmental hazard. The chain of failure concept derives from studies in the context of industrial risk analysis and organisational studies regarding the human/machine interface in complex and hazardous plants (chemical and nuclear). In those fields of study, the concept has been introduced so as to account for the many alternative ways in which a disastrous outcome may be reached. The same, however, can be said regarding complex urban and metropolitan environments, where many potential induced hazards coexist in a relatively small space. Industries, gas conducts, electrical lines, landslides may all be triggered by an earthquake, increasing severely the magnitude of a seismic event, as demonstrated by the earthquakes that occurred in the last decade in urban contexts, such as Kobe in Japan and Ismit in Turkey. The way to achieve satisfactory representations of what might happen as a consequence of an earthquake in a complex urban and metropolitan context is clearly still rather long. The inclusion of more systems in the assessment, including economic and social, is crucial to enhance our understanding of the overall societal response to such an extreme event. The experiences that have been presented are going in that direction, accepting some level of under-modelization and partial quantification, to gain in capacity of including as many social, economic and systemic factors as possible.

References A. Bernardini, La vulnerabilità degli edifici. Valutazione a scala nazionale della vulnerabilità sismica degli edifici ordinari, CNR-Gruppo Nazionale per la Difesa dai Terremoti, 2000. M.P. Boni, S. Menoni, F. Pergalani, V. Petrini, Developing complete event scenarios starting from lifelines damage assessment, Published by Elsevier Science Ltd. All right reserved, IV European Conference on Earthquake Engineering, Paper Reference 513.

Irene Cremonini, Sandra Vecchietti, Il preliminare del piano dio recupero antisismico del centro storico do Rosario, Urbanistica – Rivista semestrale dell’Istituto nazionale di Urbanistica, n.117 Dicembre 2001, Anno LIII, pp.35-38. European Commission, ARMONIA Project. WP2: Collection and evaluation of current methodologies for risk map production. Del. 2.1 Report on current availability and methodology for natural risk map production, Project funded by the European Community under the Sustainable Development, Global Change and Ecosystems, (2005).

Grandori G., Cost-benefit analysis in earthquake engineering, in "Proceedings of the Seventh European Conference on Earhquake Engineering", Settembre 20-25 1982, Athens, Greece, 1982. 20

Haas J., Kates R., Bowden M. (1977). Reconstruction following disasters. Cambridge University Press, MIT. INU, Istituto Nazionale di Urbanistica – Sezione Emilia-Romagna, Rischio sismico e pianificazione nei centri storici, a cura di Irene Cremonini, Alinea Editrice, (1994). Scira Menoni, La valutazione di vulnerabilità territoriale applicata ai rischi naturali: alcune riflessioni, Geologia dell'Ambiente - Periodico trimestrale della Società Italiana di Geologia Ambientale, (Anno VIII- n. 2/2000). S. Menoni, F. Pergalani, M.P. Boni, V. Petrini, Lifelines earthquake vulnerability assessment: a systemic approach, Soil Dynamics and Earthquake Engineering 22, (2002), 1199-1208. Floriana Pergalani, Vincenzo Petrini, Scheda tecnica per la valutazione dello scenario di danno e del rischio sismico, (Dicembre 2003).

Presidenza del Consiglio dei Ministri, Ministero del Lavoro e della Previdenza Sociale, Dipartimento della Protezione Civile, Gruppo Nazione per la Difesa dai Terremoti (GNDT), Censimento di vulnerabilità degli edifici pubblici, strategici e speciali nelle regioni Abruzzo, Basilicata, Calabria, Campania, Molise, Puglia e Sicilia, Volume 1° - Relazione Generale, (1999). Regione Emilia Romagna, Assessorato Programmi d’Area e Qualità Edilizia – Direzione Generale e Pianificazione Urbanistica, Conservazione, riuso e programmi complessi. Dieci anni di studi, piani, restauri, Copyright Regione Emilia Romagna (1997) REGIONE LOMBARDIA-Settore ambiente ed energia, Servizio geologico e Istituto di ricerca sul rischio sismico, Cnr (1996) - Determinazione del rischio sismico a fini urbanistici in Lombardia. Vertemati, Milano.

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