4.4 Mitigation options for natural hazards, with a ...

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4.4 Mitigation options for natural hazards, with a special focus on volcanic eruptions M. Indirli ENEA, Bologna, Italy

E. Nigro Department of Structural Engineering, University of Naples “Federico II”, Naples, Italy

L. Kouris Department of Civil Engineering, Aristotle University of Thessaloniki, Greece

F. Romanelli Department of Geosciences, University of Trieste, Italy

G. Zuccaro PLINIVS Centre and University of Naples “Federico II”, Naples, Italy

4.4.1 Introduction The main risk assessment procedures (hazard identification, hazard profile, combination of hazards scenarios, inventory assets, estimate losses, mitigation options) have been already discussed, from a general point of view, in the Section II.4. 4.4.2. The effect of water 4.4.2.1 Description Floods concern more than 65 million people per year in the world; they cause the major economical damages and are responsible for about 60% of the fatalities due to natural catastrophes in the world. River floods River floods are one of the main hazards encountered by people living in the whole European Union. Since these floods can take numerous forms (such as flash floods, estuarine floods, mud floods, etc.), almost all kinds of landscapes can be impacted. In the past decades, an increase in terms of frequency and of importance has been noticed, related to numerous causes: modification of land occupation, erratic river banks management, and the effects of climate changes on storm events frequency. Coastal floods Highly energetic wave regimes, some negative effects from coastal interventions, littoral occupation, exterior interventions in harbours, the weakening of river sediment supply, the generalized sea level rise and other effects of climate changes can be pointed out as the main causes of the increasing number of constructions exposed to waves. Overtopping and flooding are being more frequent events on the coastal zones, jeopardizing buildings and infrastructures. Erosion Most of the European coastal states are affected by coastal erosion, some of them in spite of the coastal protection works done. In addition, another 4 700 km have become artificially stabilized. The main causes for coastal erosion are the generalized sea level rise, caused by climate change, some negative effects from coastal interventions, littoral occupation, exterior interventions in harbours, and river sediment supply reduction Tsunamis Tsunamis are series of waves created by the fast displacement of huge volumes of water (an ocean for instance) strongly and rapidly affected by a natural phenomenon at a huge scale. Generally, they can be initiated by earthquakes, submarine volcanic eruptions or landslides (seabed slides) for example, but not by strong winds whose impulsion is not short and strong enough. The effects of a tsunami can be classified as insignificant to catastrophic regarding

coastal population and constructions. The energy of the phenomenon is sufficient to project any kinds of objects found on its path (ships for instance but also any kind of debris) and sometimes far from the coast. Their combination is powerful enough to shear weak brittle houses at their base or to submerge and to create bending actions on rather high constructions depending of the wave height. Details can be find in: Coelho et al., 2004, 2008 and 2010; Rossetto et al., 2010. 4.4.2.2 Mitigation actions against water effects The European Parliament presented a Directive (2007/60/CE) in 23 October 2007, related with the evaluation and management of flood risks. The document intends to reduce the risk of damaging consequences associated to floods in human being health and lives, environment, cultural patrimony, economic activities and infra-structures (Directive, 2007). In the USA, the Federal Emergency Management Agency recently (June 2008) published guidelines for the design of structures for vertical evacuation from tsunami (FEMA, 2008). In the UK, a new tsunami generator is being built that will be capable of generating a complete tsunami within a physical model (Allsop et al. 2008). One of the usually preferred solutions to solve erosion problems is beach artificial nourishment. This can represents a very expensive solution, when the sedimentary deficit is very high, and there is not any sand deposit availability to such high values. However, it is essential to try to mitigate coastal erosion processes in specific locations. At the moment, the so-called hard coastal defences are indispensable to protect some of the existing settlements, but should be foreseen an adequate plan of monitoring of the existent coastal defence structures. Regarding the political point of view, it is crucial to regulate urban seafront extension. In some cases, the policy options of managed realignment – identify a new line of defence and re-settle the populations in the hinterland – have to be considered. The solution for coastal erosion problems must pass through a compromise between the passive acceptance of erosion, some beach nourishment and coastal intervention for urban front protection. With regards to tsunami and coastal floods, increasing numbers of coastal properties or assets are exposed to wave attack due to changes to land use and increases of sea levels (and/or wave action). Improved management of anthropogenic impacts may help reach goals such as the reduction of human lives losses, reduction of damage in structures and coastal buildings, preservation of natural environments, increase in evacuation capacities, location of new structures and buildings out of danger areas, and relocation of existing structures and buildings. With the advent of new techniques such as Geographical Information System (GIS) and Remote Sensing (RS) for data processing and classifying coastlines, it is needed to consider the incorporation of a huge amount of data into a global open-ended and interrelated coastal classification system, in order to evaluate inundation maps and their impact towards the natural and built environment. Another aspect is related to the role of existing ecosystems (coral reef, seagrass bed, mangrove forests, beaches and dunes, beach forest and other dense forest) and their influence on the intensity of flood damage, as “buffers” for normal waves, storm waves and tsunami. However, the benefits of these “buffers” is strongly debated. For instance, based on data from the 2004 Indian Ocean disaster, Kathiresan and Rajendran, (2005), Liu et al., (2005), Marris (2005), Morton et al., (2006), and Usha et al., (2009) observed that intact sand dunes, rock platforms, mangrove forests, coral reefs and barrier islands all offered enhanced protection against wave impact, flooding and scour. Feagin et al. (2010), throw doubt on some of these findings and call for controlled physical experiments to be carried out to investigate the effects of vegetation on coastal defense from storm surges and tsunami (Rossetto et al., 2010). In any case, the scientific community agree on highlights gaps in knowledge and the necessity of further research. The main mitigation strategies against flooding are the following: - mapping of the flood prone area; - land use control, meaning that no major development should be allowed in the areas subjected to flooding; - construction of strong engineered structures to withstand flood forces; - flood control in order to reduce flood damages, including flood reduction, diversion and proofing.

Approaches to limit disruption and damage from flooding have changed significantly in recent years. However, this approach needs integrating: enhanced defences and warning systems with improved understanding of the river system and better governance, emergency planning and disaster management actions. Because the risk is increasing in most of the urban areas due to their fast growing extension involving larger zones, it is necessary to provide efficient models of calculation in order to define different likely scenarios to help in choosing the best strategies. In each country, many institutions are working in that goal to create realistic rescue plans. Flood risk is generally highly localized and as a result, difficult to quantify. Existing maps should be updated, taking into account the effects of climate changes and recent urbanization. Land use plans with identified flood hazard areas, inundation areas, evacuation plans and rehabilitation areas are required in all the regions in the world where likely floods exist. In the industrialized countries, this work is more or less operational and dynamic models allow the development of flood hazards to be evaluated and the safety measures established. Nevertheless, as an example, the consequences of the Hurricane Katrina on New Orleans in August 2005 have shown that, even if the US which can be considered as a modern country, the predictive system and the protected measures were not sufficient, that the levees were not designed to be safe enough and that the rescue organisation was not well prepared in front of such a disaster. In low level countries, the sporadic urbanisation, the unsustainable constructions and the inadequate drainage systems are increasingly causing flood disasters. Integrated and holistic plans for larger water basin areas are strongly needed. As the climate evolution seems to be difficult to be predicted, it becomes imperative for the countries to increase their efforts in monitoring and preparing emergency models. Flood modelling software can help to simulate various scenarios and take proactive steps. It is possible to consider which zones or streets risk getting flooded first, the sewer conducts that will overflow first and plan the investments needed to prevent them. Wastewater software can be used to manage sewerage effectively. To avoid streaming and to define realistic limits of permeability in urban areas by creating water storage possibilities, as green spaces or buffer zones for instance. The elevation of the sea level and the effects of glacier melting have to be taken into account in the modelling. In the significant case is given by the hurricane Katrina, an updated code has been provided (FEMA, 2006a-b); the main recommendations (both for flood and wind) include the adoption of updated building codes (IBC, 2006; IRC, 2006; NFPA 5000, 2006), incorporating flood load (ASCE, 2006a) and flood-resistant construction standards (ASCE, 2006b), with particular regard to foundations. 4.4.3. The effect of snow 4.4.3.1 Description 4.4.3.1.1 Exceptional snow loads Extreme snow is a natural action resulting from heavy snow falls in areas where snow is usual environmental load or an action resulting from any snow loads in regions not normally exposed to snow falls. Repeated snow events that do not have time to melt and the rain that saturates the snow, which greatly increase its weight, can accumulate and significantly surpass the roof design’s live load and can causes a roof structure to fail. Snow covers on roofs are susceptible to drift action, which leads to removal of snow from some areas and an accumulation in others, and can bring to the extreme design states of snow loads. The collapse of roofs due to heavy snow accumulation may be considered as a catastrophic event and the risk-based approach may be utilized for safeguarding constructions against extreme snow actions. For altitudes smaller than 1500 m, exceptional snow loads are specified in EN1991-1-3:2003, and the code is based on the assumption of a return period equal to 50 years. Exceptional snow loads are considered as accidental loads (EN, 1991a-b). 4.4.3.1.2 Avalanches

Avalanches are one of the infrequent actions not taken into account in the Eurocodes. It is possible to identify two main types of avalanches (Givry and Perfettini, 2004) depending on the state of the snow: dry snow (or powder avalanche) and wet snow avalanche. The difference between these two kinds of phenomena defines their mode of failure, their way of displacement down the slope and their relative power. Being slower, wet snow avalanches appear to be less dangerous for humans than dry avalanches, but regarding construction it is the opposite. Nevertheless, if the robustness of the construction can be strongly affected by wet snow avalanches, the openings are affected by dry snow avalanches due to its related high pressure. 4.4.3.2 Mitigation actions against snow effects The design of building structures is largely based on statistics of extreme or catastrophic events which are usually utilized by applying the theory of extremes. Extreme snow loading accounts for several roof collapses each year. Lightweight roof structures, especially long span flat roofs of shopping centers, sport and concert halls, stadiums, railway and bus stations, metal dome roofs of tanks and so on, are the most frequent types of constructions collapsed during recent years (Zuranski, 2007, Pavlov and Vostrov, 2005). Snow loads on roofs depend on different climatic variables (the amount and type of snowfall, the specific gravity and other snow properties, wind, air temperature, amount of sunshine, etc.), on roof variables (shape, thermal properties, etc.), on site exposure and surrounding environment variables. Calculation of extreme snow loads is largely based on statistics of extreme events which are conventionally utilized by the theory of extremes. Because this method may give very misleading results, purely empirical fit to the observed extremes is recommended (Wolinski, 2007 a-b) Building structures may be considered as structural systems, i.e. bounded groups of interrelated interdependent or interacting elements forming an entity that achieves a defined objectives. Therefore, the approach based on the generic system characteristics such as exposure, robustness and vulnerability may be utilized for design and assessment of concrete structures (Steward & Melchers, 1997; Faber, et. al., 2006). An exposure is related to any event with the potential to cause damage to the structure (loads, corrosion, errors or other disturbances). Robustness is considered to be a measure of the degree to which the specified or unpredictable perturbations influence performance of a structure and is characterized by means of the risk associated with all indirect consequences of its failure or collapse. Vulnerability of a structure is defined as the measure of extend to which changes would harm a structure and characterizes the direct risk associated with its damage or failure. New methods, mainly the purely empirical method of determining extreme snow loads for structural design should be tried in order to compare with the extreme value theory via Gumbel model which is widely used in building codes to estimate snow loads. The approach to design and assessment of the lightweight roof structures subjected to infrequent loading conditions (heavy snow storms, unusual patterns of snow cover, combined snow, wind and ice actions, etc.) based on assessment of risk characteristics should be introduced as a helpful supplement to design and assessment procedures. Other details are given in: Ellingwood and O’Rurke 1985; Gooch, 2002; Mihashi et al., 1989. Avalanche mitigation can be done trough active and passive defences: a) Active defences: they aim to reduce the avalanche occurrences; regarding this aspect, it is for instance possible: to activate small explosions in order to create little avalanches to clean the slopes; to prevent skiing on slopes when a risk exists that an avalanche could be initiated by a skier. b) Passive defences: some actions can be provided to reduce the avalanche impacts; for instance, it can be efficient to build avalanches barriers and walls, to optimise the design and the orientation of constructions or to organise mountain rescue. A major possible development is relevant to the prediction of the occurrence of the avalanche phenomenon (Burlet, 1999) at the Ski resort scale. It is based on the idea that mechanical models can help avalanches predicting as mechanical models do for land slopes. The development of this approach needs the knowledge of the snow layers (type, thickness and mechanical properties) at each time where the risk assessment is needed.

Another possible development concerns the avalanche dynamics and more precisely its impact on works (Ma, 2008) at the slope scale. It aims to estimate the avalanche action on an avalanche wall used to protect a road. It is based on the idea that an avalanche can be modelled as a granular flowing. Details can be find in: Muzeau et al., 2007; Platzer, 2006; Talon et al. 2010a-b. 4.4.4. The effect of wind 4.4.4.1 Description 4.4.4.1.1 Extreme winds Cyclones, hurricanes, tornados or typhoons are extreme winds whose dynamic action leads generally to severe damages on constructions. To be initiated, tropical cyclones need certain thermodynamic conditions to be respected above a large mass of warm water. Therefore, they form above seas or oceans. They are named hurricanes in the Atlantic Ocean and typhoons in the Pacific Ocean. Tornados are initiated above the earth during a severe storm when special thermodynamic conditions are found between huge cloudy masses and winds. 4.4.4.1.2 Cyclones Three types of cyclonic perturbations are commonly defined: tropical depressions, tropical storms and tropical cyclones (Chaboud, 2003). A tropical cyclone is constituted by an eye at its centre, which is a relatively warm and calm zone, surrounded by an area about 16–80 km wide in which the strongest thunderstorms and winds circulate around it. Up to now, the extreme wind speed due to a tropical cyclone is estimated to be equal to 305 km/h. To be initiated and sustained, tropical cyclones need large unstable volumes of warm water (more than 26°C over 60 m in depth) so, their strength decreases over land because of the lack of water. 4.4.4.1.3 Tornados Much smaller than a tropical cyclone regarding its influence diameter, a tornado is a violently rotating column of air starting from the lower part of a cumulonimbus cloud and in contact with the earth. The damages on constructions are generally localised but very important due to the high speed of the rotation. In most cases, a cloud of debris collected on the way, moves around the funnel at its lower part and it contributes to increase the damages. A powerful tornado may extract light constructions from their foundations. Most of the tornadoes create a very localised strong wind whose speed may reach 175 km/h. Their lower part is generally about 100 m and they travel only on a small distance (about 10 km) before they dissipate. Nevertheless, much more powerful tornadoes have been observed: with a wind speed close to 500 km/h, with a base diameter close to 1.5 km and whose way on the ground may be longer than 100 kilometres. 4.4.4.2 Mitigation actions against wind effects The tremendous losses year by year indicate that structural safety and serviceability criteria are not fulfilled. Experience from past disasters must be considered along with advanced wind monitoring related research for safer and more complete design and construction codes. Structural engineers face a new challenge in the new millennium, due to the effect of rapid climatic changes, which influences directly the engineering society which needs to adjust to the unexpected and severe natural catastrophic events. Building codes are supposed to be strict enough to protect buildings from high wind loads. In some cases, excessive damage is noticed during hurricane events in spite of the fact that the recorded wind speeds were lower than the maximum recommended by the code design wind speed (Kareem, 1984). Local and international building codes have been revised several times over the last few decades, but the losses and damages due to wind are still considerably high (ABI, 2003; Munchener Ruck; 2006 and 2007). These facts indicate the necessity of advanced research in the area of extreme wind action and low-rise buildings interaction. The nature of extreme wind phenomena is very complex and researchers must focus on the understanding of such events. Notwithstanding the relevance of these questions, the structural response of low-rise structures subjected to extreme wind loads

must be evaluated through model and full-scale studies, in order to be able to conclude about safe and economical design parameters. Other details are given in: Doudak et al., 2005a-c; Holmes 2001; Islam and Peterson, 2003; Minor, 2005; Simiu and Scanlan, 1996; Witham, 2005; Zisis, 2006; Zizis and Stathopoulos, 2008; Solari, 2007. 4.4.5. The effect of landslides, rockfalls and flowslides 4.4.5.1 Description Landslide describes a wide variety of processes that result in the downward and outward movement of slope-forming materials including rock, soil, artificial fill, or a combination of these. The materials may move by falling, toppling, sliding, spreading, or flowing. The various types of landslides can be differentiated by the kinds of material involved and the mode of movement. Other classification systems incorporate additional variables, such as the rate of movement and the water, air, or ice content of the landslide material. Although landslides are primarily associated with mountainous regions, they can also occur in areas of generally low relief. In low-relief areas, landslides occur as cut-andfill failures (roadway and building excavations), river bluff failures, lateral spreading landslides, collapse of mine-waste piles (especially coal), and a wide variety of slope failures associated with quarries and open-pit mines. The conventional stability analysis of slopes where sliding is possible along some definable surface is usually preformed by calculating the factor of safety, i.e. by comparing the shearing resistance available along the failure surface. With the shearing stresses imposed on the failure surface. Most analytical methods are based on limit equilibrium, with typical failure forms such as infinite slope or finite slope with planar or curved failure surface considered. However, the recently introduced performance-based approach, emphasis is placed not on whether the slope is stable or unstable, but on the magnitude of deformation after failure. Several techniques are currently available to asses the post-failure velocity and travel distance of the moving mass. The basic model assumes that during the shaking a slope will suffer displacement only when the ground acceleration exceeds a threshold value, the critical acceleration, which can be derived from the static factor of safety of the slope in question. The sliding mass will continue to move until the shaking drops below the critical acceleration. If the cumulative displacement caused by shaking, known as Newmark displacement is sufficient to cause a reduction in the shear strength of the soil or rock mass then a re-calculation of the slope stability is carried out using residual shear strength parameters to establish whether failure occurs. Thus the analysis is bi-linear, allowing for a change in the strength parameters of the slope forming materials based on the deformation of the slope. 4.4.5.2 Mitigation actions against landslides and flowslides 4.4.5.2.1 Landslides as a secondary event of earthquakes and eruptions Landslide and flowslides can be surely considered as one of the most dangerous slope movements, for their capability to produce casualties and remarkable economic damage. Such phenomena are widespread in many countries and they involve different kind of soils, generally in a loose state, which in the post failure stage collapse and rapidly reach the toe of the slope; the initial mobilised mass often increases during its path downslope either by inducing additional slope failure and/or by eroding the stable in place soils. Significant examples of this type of slope movements occurred in several areas of the world, as those periodically occurring in the Campania Region triggered by critical rainfall events. They involve unsaturated pyroclastic soils – originated by the explosive phases of the Somma-Vesuvius volcano – which mantle the limestone and tuffaceous slopes over an area of about 3000 km2 . However, landslides may be also secondary events of earthquakes or eruptions, as several historic data show. For example, one of the most significant effects of the 1994 Northridge, California, earthquake and of the 2001 El Salvador earthquakes was the triggering of thousands of landslides over a broad area. Some of these landslides damaged and destroyed homes and other structures, blocked roads, disrupted pipelines and caused other serious damages. A further type of landslides may be produced by “rapid avalanches” of intimately mixed snow and hot

pyroclastic debris during a volcano eruptions, as for the eruptions at Mount St. Helens, Nevado del Ruiz, and Redoubt Volcano between 1982 and 1989. The types of landslides previously described may be events induced by the eventual eruption of the Vesuvius and by the connected seismic motions. In Chapter 3.4 of this Report the possible effects of such kinds of landslides on the urban areas are investigated and mechanical models deduced utilising also hydrodynamic concepts are introduced; the models are capable to interpret the effects of the landslide impact on the constructions and the collapse mechanisms of various types of structures. Based on the quoted mechanical models and hydrodynamic concepts, the main guidelines of two technical codes devoted respectively to the rebuilding and reparation of constructions in areas with high landslide risk may be applied in order to obtain a risk mitigation for the effects of landslides. 4.4.5.2.2 A Technical Code on the structural design in urban areas with high debris-flow-risk The serious damages produced in the urban areas by the hydrogeological disaster occurred in Campania put in evidence into the civil community the fundamental problem of a suitable territory use, with particular care to the possibility of reparation or rebuilding of the constructions damaged or destroyed by landslides. Thanks to the significant work of the Operating Unit stated by the Civil Protection Agency at the University of Salerno, the immediate answer was the definition of a “red line”, which perimeter individuated the areas with high debris-flow-risk on the base of their geomorphologic characteristics. Based on the interpretation of the surveyed building damages and mechanical characteristics of the dynamic impact of the debris flows on the constructions, the main guidelines of a technical code devoted to the rebuilding of constructions in areas with high landslide risk is reported in the following. Among other things, the criteria to evaluate the design actions due to debris flow impact and the types of buildings and structural systems more efficient to sustain the same actions are suggested. The mechanical models described in Chapter 3.4 have represented a worthwhile contribution to the definition of the technical code, approved by the Campania Regional Government (Italy), in order to allow suitable operations of rebuilding of in urban areas with high landslide risk. Being socially unacceptable to delocalise the population hit by the above described disaster, Campania Region Authorities have provided the areas having a significant debris-flow-risk with a specific code, partially based on the results summarized in Chapter 3.4, to allow to rebuild constructions capable to resist to debris flows phenomena. The code in argument refers to the areas of the cities, where there is a residual risk of debris flows, also taking into account the effects of the foreseen protection works able to reduce or eliminate the debris-flows-risk. These protection works are mainly: • naturalistic engineering works, to prevent irregular concentration of water flows or local soil collapse, which could constitute the primer of more general landslides; • hydraulic works, to regularize the flows and to prevent the detachment of unstable pyroclastic layers along the valleys; • dams, to contain the debris flows phenomena and to protect the built-up area. 4.4.5.2.3 Main aspects of the Technical Code The Technical Code on rebuilding (Campania Region Government, 2001) is based on the fundamental remark that it results practically impossible that ordinary built constructions resist to the hydrodynamic action due to the debris flow impact. Therefore, when it is impossible to protect the construction with specific works or to deflect the flow, the defence strategy consists in reducing the impact surfaces adopting a construction typology with isolated columns at the ground floor. In this case it is necessary to quantify the impact actions, mainly deriving from the impact velocity. With this purpose, the territory of interest has been subdivided in areas with different expected velocity: A) High velocity expected zone: 10 m/sec B) Medium velocity expected zone: 7 m/sec C) Low velocity expected zone: 5 m/sec The consequent horizontal actions are generally very strong compared with ordinary seismic or wind actions; in fact, orientation values of the debris flows action are the following: A) High risk zones: hydrodynamic pressure: 150.0 kN/m2 B) Medium risk zones: hydrodynamic pressure: 73.5 kN/m2

C) Low risk zones: hydrodynamic pressure:

37.5 kN/m2

The main contents of the Technical Code can be summarised in the following points. 4.4.5.2.4 Evaluation of the debris flow impact actions The actions produced by the impact of the debris flows on obstacles depend on velocity, density, height and direction of the stream, on shape and dimensions of the impacted obstacle, on the presence of masses transported by the flow. The resultant thrust is expressed as the sum of the dynamic and static thrusts: Sc,1 = Sc,1d + Sc,1s

being, with reference to walls of rectangular shape (see Figures 4.4.1a,b): • Sc,1d = ρc v 2 hc b cos 2 θ the dynamic resultant thrust

(20)

(21)

1 Sc,1s = ρc g ho2 b the static resultant thrust (22) 2 3 • ρc debris flow density (ρc = 1500 kg/m , unless more accurate evaluations) • v debris flow velocity (in ms−1): • θ angle of the flow direction with respect to the axis normal to the impacted surface • g gravity acceleration (9.81 ms-2) • ho = hc + d, height of the impacted surface (in m) • b width of the impacted surface (in m) • hc height of the debris flow (hc = 3.00 m in all the zones, unless more accurate evaluations) • d depth of the laying plane of the surface with respect to the external land plane (in m) In the case of fixed obstacle completely immersed into the flow, as well as r.c. columns at the ground floor, the resultant dynamic thrust on the obstacle holds:



Sc,2 = Cf ρc v2 h c b

(23)

Cf being the shape coefficient of the obstacle, variable in the range (0.5 ÷ 1.1). 4.4.5.2.5 Safety checks The above defined actions due to debris flow are considered “design values”, so that they have to be utilised in the ultimate limit state checks adding to the other permanent and variable design actions, unless wind and seismic ones. If the check of the structure is performed according to the “allowable stress method”, the debris flow actions have to be reduced by dividing for the load partial safety factor γc,f = 1.5 . 4.4.5.2.6 Constructive provisions In order to reduce the actions and the effects of the debris flows on structures, the following provisions hold: • the structure has to be designed with reference to the actions previously defined; • the impact surfaces of the construction have to be reduced adopting appropriate shapes and planimetric distributions; • the impact surfaces at the ground floor have to be reduced, distinguishing the cases of tangential action and orthogonal action of the debris flows: - in the first case, buildings with external walls at the ground floor are allowed, making them able to sustain the hydrostatic pressure; - in the second case, buildings with external walls at the ground floor must be avoided, realising framed structures with isolated columns at ground floor able to sustain both hydrostatic and hydrodynamic actions. 4.4.5.2.7 Other topics Further topics treated in the code provisions concern:

• the design of direct and indirect foundations of buildings, taking into account the horizontal actions due to debris flow impact; • the design of the structure, reducing the impact surface of the single members by means of appropriate cross-section shape and planimetric position; • the design of structures, avoiding distance between columns less than 5.0 meters in order to prevent the formation of accidental obstructions to the free flow.

Figure 4.4.1a. Dynamic thrust on a walls of rectangular shape.

Figure 4.4.1b. Static thrust on a walls of rectangular shape.

4.4.5.3 Technical Code on repairing of existing buildings The Technical Code on repairing of existing buildings (Campania Region Government, 2002) assumes that these buildings are not able to sustain the orthogonal dynamic impact of debris flows. Therefore, the repair of damaged buildings located in areas with high debris flow risk is only allowed in the case of tangential impact of the flow against the building, thanks to the local orogra-

phy or protection systems. In such a case the flow action can be assumed as equivalent to hydrostatic pressure due to fluid with high mass density (ρc =1500 kg/m3). Finally, it has to be remarked that areas with high debris flow risk are inhabited from centuries or millennia, so that the dislocation of the people is not socially acceptable and it appears simultaneously necessary to reduce the risk level. This remarks led to the introduction of specific technical codes devoted to rebuilding and repairing of the constructions located in some areas of the Campania Region (Italy) interested by debris flow phenomena in the last years. These codes do not substitute the planned works devoted to the reduction of the area risk, but have the aim to reduce the vulnerability of the constructions, being aware that, notwithstanding the defence works, a residual risk remains, which should be eliminated only with an unacceptable impact on the environment. 4.4.5.4 Final remarks The general methodology, the criteria and the failure models described in the Chapter 3.4 and in the present one with reference to the case of debris flow impact on buildings may be extended to other cases of interest for the Risk Assessment for Catastrophic Scenarios in Urban Areas. For example, the phenomenon of pyroclastic flows is quite similar to the described one and requires the knowledge of the same structural data concerning buildings in order to assess their vulnerability. Also the Technical Codes, summarily illustrated in the previous paragraphs, may represent a reference in order to write guidelines concerning the refurbishment or retroffiting of existing buildings to resist to catastrophic events. Details can be found in Cascini and Ferlisi, 2003; Cascini et al., 2003; Faella and Nigro, 2003a-c. 4.4.6 The effect of earthquake This topic is widely discussed in other parts of this final report. It is necessary to stress that the adoption of revised set of rules by several Government Authorities is a step already achieved in many earthquake-prone countries, especially after the Northridge (1994) and Kobe (1995) seismic events, but also following the primary school collapse of San Giuliano di Puglia, Molise Region 2002, Italy. 4.4.7 The effect of volcanic actions Several other sections are dedicated to the volcanic question. This part, after a brief description of the effects, focuses in particular the mitigation options. 4.4.7.1 Description The effects of a volcanic eruption on built environment have been investigated in the last 15 years, defining a comprehensive framework of studies, surveys and simulations that include all the different eruptive phenomena and their possible impacts on existing buildings and infrastructure. Nevertheless, in order to define a design methodology for the technological retrofit of structures in volcanic risk-prone areas, a different approach is needed, starting from the basic consideration that the cumulative effects given by a complex eruptive scenario (such as a SubPlinian or Plinian eruption) produce extremely variable impacts on constructions, depending by the specific time history of the event and by the building typologies and their level of vulnerability. This peculiar approach has been recently formalized in order to evaluate the impact of a Sub-Plinian eruption in Vesuvius area (Zuccaro et al., 2008), through the development of a numeric model for the definition of impact scenarios. The study of building technologies for the mitigation of volcanic risk is strongly connected to the model. It has been developed as a part of SPeeD project, funded by Italian Civil Protection Department. The parameters assumed for the design of specific technical solutions come from the elaboration of data by SPeeD and Exploris project, and the proposed retrofit technologies are directly referred to conventional building types inside Vesuvius and Campi Flegrei area. The first part of the study analyses the mitigation strategies referred to each single eruptive phenomenon, in order to define different technical options for the mitigation. The second part proposes a comparative methodology for the assessment and the choice between possible solu-

tions based on conventional and innovative technologies, including the use of advanced materials, which must meet specific requirements of safety, reliability, durability and integrability. A specific attention is given to building site issues related to logistics and on-site operations, taking into account the need to make widespread interventions in risk-prone areas and preferring solutions – with equal performance levels – characterized by quickness and easiness of installation or by low oper ating costs. 4.4.7.2 Mitigation actions against volcanic effects on structures 4.4.7.2.1 EQ - Earthquake The seismic events that characterize an eruptive phenomenon can be generally considered of low to medium intensity. Nevertheless, the cumulative damage caused by the sequence of earthquakes in various stages of the eruption produces a progressive increase in the level of expected damage. According to the sequence of phenomena characterizing the eruptive event, more conditions can occur and raise the damage caused by the earthquake. In particular, the ash fall creates a progressive overload on the roofs, and even when it doesn’t result in a partial collapse of the floor, it brings to an increase of reactive mass of the building, thus modifying the response to seismic action. The building types with high vulnerability, with particular reference to masonry structures, would then suffer more damage than for a single event comparable to the maximum intensity expected in case of a Sub-Plinian eruption. Generally speaking, considering the high seismic vulnerability levels and the construction density in Vesuvius area, cost-effective mitigation measures should be provided. It is possible to choose cheap and reliable technical solutions (such as iron chains in masonry buildings, the insertion of infill panels or resistant elements in soft floors of reinforced concrete buildings), but also to adopt, in case of seismic reinforcement, specific solutions able to respond effectively also to other volcanic phenomena, such as pyroclastic flows or ash fall. In this context, one solution is the construction of pitched roofs by overlapping light structures in CFS (Cold Formed Steel). This allows to chain vertical structures by increasing the resistance to seismic actions (box behaviour) and simultaneously prevent the deposit of ashes and the structural risks related to overloading of the roof, also in consideration of a possible earthquake following the ash fall phase. At the same time, should be avoided the employ of widely used reinforcement systems not satisfying the conditions of volcanic risk, such as FRP (Fiber Reinforced Polymers) in proximal areas, whose effectiveness is seriously reduced by the possible impact of pyroclastic flows. In fact, the high temperatures produced could affect the polymer matrix, whose physical and mechanical properties degrade in range above 60-80°C, with the consequent failure of the system caused by the loss of adhesion of the reinforcement to the walls. In this cases alternative technologies should be adopted, compatible with the environmental conditions related to a volcanic event, such as FRCM (Fiber Reinforced Cementitious Matrix) systems, able to withstand high temperatures while preserving the mechanical properties. Global mitigation strategies related to seismic risk in case of a volcanic event may include planning for widespread interventions, defining the areas that require priority actions, such as the building curtains facing the main transport routes and escape routes identified by the Civil Protection Emergency Plan, in order to ensure safe evacuation routes during unrest phase, characterized by increased seismic intensity. 4.4.7.2.2 PF - Pyroclastic Flows Pyroclastic flows can produce high damages to the built environment in areas near to the vent. Although they would have a limited action range, the effects can be critical because of the combination of mechanical impact and thermal stress on the vertical surfaces of buildings. The main damages come from the impact on openings, particularly vulnerable to pyroclastic flows. In these cases, although not resulting a static failure of the building, a fire risk is associated with the flow passage inside the building following the crash of the openings. In the case of Vesuvius and Campi Flegrei, pyroclastic flows can cause lateral pressure impact within a range of 0.5 and 10 kPa, and thermal stresses ranging between 150 and 450 °C. In Campi Flegrei the probable location of the vent, near to densely populated areas (including the west area of Naples), the impact of pyroclastic flows would be particularly serious, while in the

case of Vesuvius is expected a decay of the initial power due to the distance of the built areas from the vent. Mitigation strategies mainly concern the reinforcement of infill panels in r.c. buildings and measures for the protection of openings (Figure 4.4.2). When reinforcing infill panels, the goal is to increase the impact resistance while withstanding the high temperatures produced by the flow. Currently used techniques for the seismic reinforcement of infill panels are generally effective to prevent them from breaking due to pyroclastic flow, however, as noticed above, the employ of currently used technologies that are particularly sensitive to temperature should be avoided. In the absence of specific constraints to envelope system modification, the goal of increasing infill panels impact resistance may be achieved by overlaying existing facades with coatings made of advanced materials offering high thermal and mechanical performances in very low thickness. It is the case of UHPC (Ultra High Performance Concrete) components, which can be cast in very large panels and show high durability and resistance to aggressive environment. These operations allow also to obtain additional performances, such as the increase of shear strength in the plane, where the panel is placed within the structural grid, or the increase of thermal resistance, where combined with a layer of insulation or with a ventilated facade system. The use of low thickness UHPC panels may also be suitable for the construction of temporary and removable systems to protect archaeological areas and sites of historical and artistic interest subject to the risk of pyroclastic flows. Protection of openings is an essential mitigation measure in relation to pyroclastic flows, as it allows minimizing the risk of fire related to penetration of the flow inside the buildings. At the same time the technical solutions provided should be able to withstand the mechanical stresses related to the pressure of the flow itself, but also to the potential presence of debris that can impact as "bullets" on openings surface. Borrowing technologies used in tropical areas for hurricanes protection it is possible to define different solutions, made with removable components or integrated into the shutting systems. In the first case, it is possible to overlay steel or kevlar sheet to existing openings, anchored along the external perimeter. Protection systems integrated into the shutting systems, unlike the removable panels, are not always able to assure an effective response to the impact of the flow, but are suitable for medium ranges of temperature and pressure or for short exposition time. It is also possible to apply special protective films on glass surfaces that can provide protection from fire and explosion. Fire safety shutters, steel or aluminum, associate the heat resistance with adequate mechanical strength. In some cases, a combination of protective films and special shutters should be provided, in order to reach the required levels of temperature resistance and mechanical strength.

Figure 4.4.2. Technical solution for theFigure 4.4.3. Technical solution for the mitigation of ash fall improtection of openings. pact on roofs through the employ of CFS structures (Alborelli, 2009).

4.4.7.2.3 AF - Ash fall

Ash fall is one of the eruptive phenomena with greater risk for existing buildings and infrastructure, as the expected impact involves (with different levels of intensity) a very large area, which definition is strictly linked to the direction and intensity of the wind, as well as to the type of eruption. In the case of Vesuvius and Campi Flegrei, the scenarios show an increase of roof loads (Table 4.4.1) due to ash fall between 1000-3000 kg/sqm inside the red zone and between to 300-400 kg/sqm for distances up to 30 km from the vent. Different types of damage may also occur in distal areas (more than 100 km from the vent), where the ash deposits are not likely to cause structural problems to buildings, but still could affect transportation networks and HVAC systems (ashes infiltration in filters and ducts). In case of eruption of Campi Flegrei, the direction with higher risk is the whole urban center of Naples, where the population is more than twice the area of the villages around Vesuvius. Ash deposit on roads and transport networks can cause considerable damages especially in proximal areas, causing localized or extended interruptions with direct effects on emergency management. Mitigation strategies, beside the need to develop an operational plan for the removal of ash on roofs and transport networks, mainly concern the repairing and reinforcement of roofing systems in order to increase the load carrying capacity (Figure 4.4.3). Pitched roofs with wooden or steel structure, reducing the deposits of ashes, would be at risk only in proximal areas where the surface of the cover present disconnections or missing parts. In this case, given the adequate inherent fire resistance of commonly used coating materials (typically clay tiles or panels of steel sheet) is enough to replace the missing elements in order to prevent the passage of hot ashes under the roof covering. In case of flat roofs it is possible to identify two main types of intervention: the reinforcement of the roof slab in order to increase the resistance according to the expected overload, or the realization of a sloped roof over the existing one. In the first case, it is necessary to define the characteristic flexural strength of different types of existing roofs in areas at risk (concrete and bricks, steel or wooden beams and hollow bricks or brick vaults, “Sap” floors, etc.), thus determining the capacity to withstand to overloads produced by ash. It is then possible to apply conventional technologies, such as integration of reinforced concrete slabs placed on the existing floors and connected to existing beams, or innovative solutions, including for instance the use of FRP (Fiber Reinforced Polymers) and FRCM (Fiber Reinforced Cementitious Matrix) systems for reinforcement of beams and joists. The main advantages of such interventions include the possibility of not modifying the existing roofing system. Table 4.4.1. Vulnerability of common roofing typologies.

A_ rf

Weak pitched wooden roof

2,0

Collapse prob. % 50

B_ rf

Standard wooden flat roof Flat floor with steel beams and brick vaults Sap floors

3,0

50

C1_rf

Flat floor with steel beams and hollow bricks R.C flat slab (more than 20 year old)

5,0

60

C2_rf

R.C flat slab (less than 20 year old) Last generation R.C. flat slab

7,0

51

D_ rf

Last generation R.R. pitched slab Last generation steel pitched roof

12,0

50

Vuln. classes

Roofing type

Load kPa

In the second case a very effective solution is to build truss or lattice structure in CFS (Cold Formed Steel) on top of the existing roof, in order to create a sloped surface. The mechanical properties and lightness of CFS structures allow the realization of a strong roofing system without a high overload on the underlying structure. The coating can be made of steel sheet, with the possibility of providing additional layers in order to offer additional benefits to the intervention of structural retrofit, such as the insertion of insulation or micro-ventilation system for en-

ergy conservation, or the integration of photovoltaic thin film for the production of electricity. Such actions may be also connected with housing refurbishment programs, allowing for instance the increase of building volume for intervention of volcanic and seismic mitigation. The realization of lightweight structures for protection from ash fall may be an appropriate solution not only for buildings but also for the several areas of historic and artistic interest (such as Pompeii, Herculaneum, Oplonti, Stabiae, etc.), which might be seriously compromised after an eruption of Vesuvius. In these areas, however, the mitigation may be invasive in terms of visual impact, and it is possible to develop provisional removable shingles. An alternative to steel roofing is the realization of UHPC (Ultra High Performance Concrete) shells, characterized by very high mechanical properties, durability, resistance to high temperatures and fire, with very low thickness required (up to 2 cm for spans of 5 m), offering effective and innovative technical solutions in terms of aesthetics and design. 4.4.7.2.4 LH - Lahars The lahars are a relevant risk factor for buildings and structures in volcanic areas. The same phenomenon may have specific characteristics depending on some variables. Damage to buildings caused by lahars can be connected to different factors. Hydrostatic and dynamic strength determine the amount of lateral forces that can bring to failure and collapse of technical elements such as openings and cladding. The density and velocity of the flow determines the magnitude of dynamic forces, while hydrostatic forces depend on the height and composition of the flow. Minor mudslides can cause abrasions of the external finishing of buildings and damage to surfaces and furnishings in case of penetration of the flow in the interior. Local effects may be caused by the transport of medium and large debris, rocks, but also uprooted trees, motorbikes and cars that can act as missiles on buildings exposed. Depending on the magnitude of the phenomenon and orographic conditions of the site, buildings of medium-low height can be buried by lahar. Further damage can be caused to structural parts of both masonry and reinforced concrete buildings, causing even serious cracks and damages, with structural failure involving foundations, due to erosion and soil liquefaction. Structural and non-structural metal elements can also be seriously damaged by the acidity of the flow. The response of structures and buildings technical elements to the action of lateral forces produced by lahars depends mainly on construction type and materials employed, as well as specific characteristics such as size in plan and elevation, number, size and position of openings, spatial distribution and presence of protective elements around the building able to divert the flow, etc. Generally speaking, structures, infill panels and ground floor openings are the technical elements most at risk in case of lahars. The reinforcement of these elements yet does not guarantee the survival of the building in case of direct impact with mudslide and debris, especially in the case of compact urban areas, where a "tunnel effect" can increase speed and height of the flow after the passage inside particularly narrow roads. For this reason the most effective mitigation strategies are related to environmental engineering interventions, to be made in risk prone areas and designed to contain or divert lahars. Measures such as retention basins, alternative artificial canals, high-strength reinforced concrete containing structures, may be appropriate solutions to mitigate risk from lahars, reducing the entity of the phenomenon in residential areas and increasing the probability of survival of the buildings. 4.4.8 Design approach for the mitigation of volcanic risk 4.4.8.1 General approach Preceding paragraphs illustrate mitigation strategies in relation to each volcanic phenomenology (EQ, PF, AF, LH). However, to ensure the effectiveness of technical options and feasibility of specific interventions, it is necessary to define a design approach that takes into account all the factors involved and the complexity resulting from the combination of effects in relation to the eruptive scenario. This approach allows a proper assessment of the effectiveness of the intervention in relation to the possible impact of eruption on the entire construction, taking into account the several factors that determine the vulnerability of a building. In particular, it has to be assumed that the survival of a building in case of eruption starts from increasing ability to respond to seismic actions, which are the first critical factor to face, also considering the ex-

pected time history. In relation to this objective, it has to be noticed that an economically sustainable intervention of seismic improvement (typically, the maximum cost should not exceed 60% of the cost of building reconstruction) determines a two classes increase of the building seismic vulnerability (i.e. A to C or B to D) and raises the chances of survival to earthquakes precursors of the eruption (between V-IX, EMS '98). However, to fully evaluate the effectiveness of such interventions in relation to the overall expected scenario, the proposed seismic reinforcement should be verified also for its contribution to resistance to roofing overload (AF) and lateral pressure (PF-LH), in order to take any corrective measure or provide additional mitigation solutions. For example, it is possible to assume that an intervention of seismic reinforcement which aims to increase the ductility of the structural system (i.e. by junction bonding of a R.C. building with FRP or FRCM systems), may be less suitable for mitigation from pyroclastic flow compared to an intervention able to increase the stiffness of the structural system, given the non-cyclic lateral action of the flow. At the same time, seismic reinforcement of horizontal structures involving roofing system, should be verified considering the overloads due to ash fall, possibly focusing on solutions that provide the superposition of a pitched roof able to enchain the perimeter walls. A similar consideration can be made about the resistance of buildings to lateral pressures produced by pyroclastic flows and lahars. Once verified the resistance to different ranges of pressure provided by the structural elements in relation to the building type (see Table 4.4.2), this should be taken as a benchmark to define the design resistance of non-structural elements (openings and infill panels). An interesting case study is related to the evaluation of mitigation scenarios for ash fall. A cost-benefit analysis was carried out involving 11 of the 59 municipalities in the areas surrounding Vesuvius involved in the AF areas. The aim is to “ensafe” about 50% of the buildings through the realization of a pitched roof over the existing flat one through CFS (Cold Formed Steel) technologies. This solution can significantly reduce the number of victims for roofs collapse, assuming that the people occupying unsafe buildings can find a shelter in buildings subject to mitigation action. The intervention is provided only for the Municipalities where the vulnerable roofs areas exceed 50% and the collapsed roof areas exceed 5%. The study has shown that compared with a total investment of around 182 million Euros is possible to reduce of about 35% the number of roof collapsed after the ash fall. Table 4.4.2. Resistance to lateral pressure of structural elements for building type. Critical pressure Technical element kPa Wooden seasonal structures 3,5 3-4 floors weak masonry buildings with deformable floors 3,5 - 5 4+ floors weak or strong masonry building 6+ floors r.c. buildings 4-5 Weak tuff walls (thickness ≤40cm, span>4m) 4 - 7,5 4-6 floors r.c. buildings 4,5 - 6 Non aseismic weak r.c. buildings 4,5 - 8 1-3 floors r.c. buildings 6,5 - 9 Medium strength tufo walls (thickness ≥40cm, span>4m) 7-9 Non aseismic strong r.c. buildings 1-2 floors weak masonry buildings with deformable floors 11 - 18 3-4 floors masonry buildings with rigid floors 1-2 floors masonry buildings with rigid floors 14 - 19

Assessment of the intervention strategy in terms of cost-effectiveness takes into account many different parameters. The priority is to define one or more "mitigation scenarios", according to a preliminary evaluation that takes into account issues such as technical, economic and social consequences related to any given scenario. Depending on the different scenarios it is possible to predict the level of effectiveness of the envisaged strategies, considering also other parameters such time and cost of rehabilitation.

4.4.8.2 Comparison and choice of technical options through indicators As stated above, in order to assess the effectiveness of mitigation actions, it is necessary a comprehensive analysis of technological options, considering the performances expressed by the employed materials and the response to primary requirements of safety, reliability, durability and integrability. Beside these considerations, it is necessary to identify additional selection criteria for different technical options. The study considers six key indicators: quick installation; storability; lightness; cost; preservation of constructive and architectural features; multifunctionality (ability of the technical solution to respond to different phenomena). The technical sheets produced report a synthetic assessment based on these six indicators, expressing a qualitative judgment that highlights the level of response given by any single technical solution for each of the parameters identified. Figure 4.4.4 shows one of the over 30 sheets of technical solutions for the mitigation of volcanic risk on buildings developed in SPeeD project, based on data and scenarios defined by the numeric model. The study is focused in particular on conventional or innovative structural reinforcement technologies for masonry and r.c. buildings; on innovative solutions for roofing and infill panels protection (including the use of advanced materials); on permanent and temporary intervention for the protection of the openings.

Figure 4.4.4. Technical sheet of mitigation solution developed in SPeeD project.

The sheets are classified in four categories: SE – Interventions on elevation structures SV – Interventions on vertical surfaces SO – Interventions on horizontal structures AP – Interventions on openings

4.4.9 Final remarks The mitigation of volcanic risk on buildings and infrastructure can significantly reduce the expected damage after an eruptive event. Even the impacts of high destructive type of eruptions, such as Sub-Plinian, can be strongly reduced by the application of one or more mitigation measures, responding to the different phenomena involved. It is therefore necessary to start from a comprehensive knowledge of the construction types available in risk-prone areas, providing specific interventions that take into account the cumulative effects given by the expected time history of the event. Hence, an effective design approach aims to put in relation technological features of existing buildings, parameters and data from probable scenarios, opportunities given by mixing together conventional technologies and advanced materials. Furthermore, considering the economical, political and social “weight” of the strategies for the mitigation of volcanic risk in densely populated areas, a valid evaluation method of the effectiveness of the proposed solutions can give scientific support to strategic choices and emergency plans. Therefore, tools for assessment and comparison between different solutions and “mitigation scenarios” are needed, trying to put together the different factors involved, such as economical and social sustainability, cultural and historical value, implication on emergency plans and on post-eruption rehabilitation and reconstruction interventions. The main reference is Zuccaro and Leone, 2010. Other details are given in: Acker, 2004; Bellomo and D'Ambrosio, 2010; Macedonio et al., 2010; UNDRO, 1991; Spence et al., 2004. 4.4.10 Mitigation actions against volcanic effects: final general considerations Mount Vesuvius is an active volcano surrounded by a densely populated area, now quiescent. However, computer simulations predict that there is a high probability of at least a subplinian eruption occurring in this century. Even if the COST Action C26 (COST, 2006) is not addressed to the issue of the evacuation plan managed by the Italian Civil Protection (Protezione Civile, 2010), and the study has been restricted to the modelling of loads acting on structures and the corresponding construction response, some general considerations are needed at the end of this Section. Due to the difficulty to interpret the premonitory signals coming from the volcano immediately before its eruption, it is not really sure that the emergency plan (foreseeing the evacuation of about 600,000 people away from the eighteen municipalities of the Vesuvius “red zone”) could be managed with a sufficient amount of time (measurable in terms of days or weeks), without a heavy risk of wrong alert; on the contrary, it is necessary to take into account that the period available for the emergency operations can be limited only to a few amount of hours. In this case, the organization of a regular evacuation procedure can be rather difficult, especially in a very crowded region. For the above said reasons, a rigorous policy of prevention (based on a multidisciplinary approach) should be considered indispensable, hoping that Vesuvius give us enough time to promote it, in order to minimize the impact of a great eruption on population and environment. The principal objective is to identify safe areas where people can live, in a secure cohabitation with the volcano. Therefore, the main goals of future researches, to be planned or improved, are the following (Dobran, 2006 and 2007): a) the development of accurate volcanic models (physical and mathematical), assessing future eruption scenarios and their consequences on the surrounding territory; b) the assessment of the global vulnerability and potential damage induced by the volcano on the entire system (population, built environment, infrastructure, etc.); c) the production of volcanic risk-reduction guidelines for communities and local/national governments; d) the promotion of a socio-cultural methodology enhancing consciousness and auto-regulation of the territory. Of course, the most important result of these studies should be the identification of alternative people settlements and the reorganization of the entire infrastructural network in the whole region, relieving the current situation to more manageable scenarios. In order to avoid a potential immense tragedy, this tremendous effort needs a multidisciplinary cooperation of the scientific community as a whole in the next decade, together with a strong institutional support in Italy and Europe.

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