SIMULATING TO EVALUATE, MANAGE AND IMPROVE EARTHQUAKE RESILIENCE IN HISTORICAL CITY CENTERS: APPLICATION TO AN EMERGENCY SIMULATION-BASED METHOD TO THE HISTORIC CENTRE OF COIMBRA

Abstract. Earthquake resilience in historical centres is significantly affected by interactions between the built environment, defined as the network of building heritage and surrounding open spaces, and hosted population. Building vulnerability, earthquake-induced effects and population's exposure mainly influence the first emergency phases. In the immediate post-earthquake evacuation conditions, people should leave their position to gather in assembly points where first responders can rescue them. Thus, joint analyses of building damage and evacuation flows along the evacuation paths become essential to determine the risk levels for the urban scenario and to provide risk-mitigation solutions. This paper tries to reach this goal by adopting a holistic simulation-based approach. A simplified vulnerability assessment method is used to evaluate the seismic performance of masonry façade walls and to estimate debris depth on outdoor spaces. An existing earthquake pedestrians' evacuation simulator is used to evaluate the probable pedestrians' choices in such evacuation post-earthquake damage scenarios. Then, risk indexes, combining damage assessment and evacuation results, are provided to quantify evacuation safety and to outline critical conditions in the urban layout. Finally, the impact resulting from the consideration of a series of resilience-increasing strategies is simulated and discussed from the proposed risk indexes. A part of the historic centre of Coimbra, Portugal, one of the oldest and most relevant Portuguese cities, is used in this work as a pilot case study. Results show how the method could be used by Local Authorities and Civil Protection Bodies to outline, analyse and coordinate resilience-increasing strategies at the urban scale

Combining Structural and Non-structural Risk-reduction Measures to Improve Evacuation Safety in Historical Built Environments

Historical city centres are critical-built environments prone to earthquake risk because of the features of the complex network of Architectural Heritage, facing Open Spaces (OSs) and the users hosted by them. Structural measures, such as building retrofitting actions, and non-structural measures, like emergency and evacuation planning, could be jointly set up to improve the safety of the Historical Built Environments since they aim to face the effects of damage across the OSs and so on the users’ movement. This work adopts a simulation-based approach to assess the individual and combined efficiency of these structural and non-structural measures. Risk indices focused on the evacuation process are used to this end, considering the final effects on the users’ movement and safety. Results show how seismic retrofitting strategies could be located in critical “hot-spots” in the urban fabric to additionally support the evacuation plan, thus reducing implementation efforts for the stakeholders

Seismic risk of Open Spaces in Historic Built Environments: A matrix-based approach for emergency management and disaster response

Abstract Earthquakes affect the safety of the users hosted in both indoor and outdoor urban built environments, especially in Historic Built Environments (HBEs). Many full HBE-scale risk-assessment methods are defined, while methodologies oriented to local analysis of meso-scale elements, such as Open Spaces (OSs), are still limited. Nevertheless, OSs play a crucial role in the first emergency phases, like in the evacuation process, since they host emergency paths and gathering areas. The seismic risk of an OS mainly depends on the combination of the damage suffered from facing buildings and the exposure, which mainly refers to the quantification of human lives. Damage levels result from the combination of vulnerability and hazard-related issues, while exposure is essentially affected by the number of OS users, whose spatial distribution is strongly time-dependent. Methods to quickly combine these issues are needed, especially in view of the deeper insights for the implementation of risk-reduction strategies (i.e. according to simulation-based approaches). This work offers a novel methodology to quickly perform Seismic Risk Assessment and Management of an OS by correlating damage levels to exposure-related issues. The method is composed of two specific matrices, which are developed according to quick literature-based approaches prone to rapid meso-scale applications in HBEs, also by non-expert technicians. The "damage matrix" links the site hazard to the building vulnerability. The assessed damage levels are combined with the users' exposure into the "consequences matrix", to estimate the risk in emergency conditions for the OS users, thus supporting decision-makers in promoting robustness/preparedness strategies

SiSMI Project–Technologies for the Improvement of Safety and the Reconstruction of Historic Centres in the Seismic Area of Central Italy

The project SISMI-Tecnologie per il miglioramento della Sicurezza e la ricostruzione dei centri Storici in area sisMIca (technologies for the improvement of safety and the reconstruction of historic centres in the seismic area)–aims to provide tools and methods for risk reduction and seismic improvement of Lazio’s cultural assets and centres, causing research, intervention policies, and planning to interact in order to support reconstruction choices and foster dialogue with local parties and enterprises. One of the SISMI project’s main elements of innovation consists of preparing modes of integration of knowledge and assessments relating to the various components of a territory’s vulnerability and seismic hazard that can be used in other seismic territories. SISMI project, tested in seismic territories of Central Italy, is a methodology of integrated, multidimensional, and transdisciplinary investigation, in the conviction that the safety of the territory and of historic and cultural assets is the result of a dynamic risk reduction process capable of guaranteeing and promoting the local communities’ resilience, in which both physical/structural and sociocultural elements collaborate

Assessment of Seismic Risk in Istanbul

The 1999 earthquakes occurred in Turkey caused destructions in every field and level in nation wide with the high number of deaths and injuries, the remarkable rates of collapsed and heavily damaged buildings and the interruption of business activities in long-term. In the last 5 year-period, various scientific researches focusing on seismic issues have investigated the relationships among seismicity, site conditions and vulnerability. Moreover, with the co-operations of central and local governments, universities and international agencies, many comprehensive projects have been carried out, such as “A Disaster Prevention/Mitigation Basic Plan for Istanbul” by Istanbul Greater Municipality - Japan International Cooperation Agency. Despite 1999 earthquakes had slight effects on Istanbul, the probability of a great earthquake (estimated to occur up to 30 years), has accelerated the attempts on risk evaluation, development of mitigation strategies, readjustment of disaster management system and so on. The primary studies on this field are focused on understanding seismicity and site conditions at large scale so that the earthquake maps produced show risky zones related to geological indicators. Aftermath of many great disasters, it has been observed that land-use decisions, demographic and economic pattern are the key components which increase or decrease the vulnerability level of settlements. In this context, the aim of this paper is to evaluate vulnerability components affecting risk levels and to explore risky zones of Istanbul. In this paper, urban and seismic indicators (i.e. site conditions, demography, land use, economy) have been aggregated and factor analysis has been used in order to reveal principal components of earthquake risk in Istanbul. According to these main factors, using cluster analysis, the critical zones of Istanbul have been indicated on urban pattern.

AN INTERDISCIPLINARY APPROACH FOR THE SEISMIC VULNERABILITY ASSESSMENT OF HISTORICAL CENTRES IN MASONRY BUILDING AGGREGATES: APPLICATION TO THE CITY OF SCARPERIA, ITALY

Abstract. The seismic vulnerability of masonry building aggregates is very difficult to determine, since it is affected by many uncertainties. The most uncertain quantities concern the historical periodization of structural aggregates. Moreover, the studies made at the urban scale can hardly be thorough, and usually the knowledge achieved on the single units is not fully satisfactory, so that the structural designer has to deal with uncompleted architectonical surveys and partial data; one of the most important problems concerns the lack of knowledge about the boundary conditions between adjacent structures. In order to perform mechanical analyses, an extensive knowledge of materials and techniques adopted is required. In this paper, an integrated methodology for the seismic assessment of building aggregate is presented. It concerns a multidisciplinary knowledge-based approach calibrated over the historical centres and the urban aggregates; the procedure joins different aspects, such as the use of modern technologies for an integrated knowledge, plans reconstructions through archival documents, laser scanner digital survey of urban fronts, non-destructive investigations of the materials. GIS and BIM platforms have been used to implement and collect data in order to perform detailed analyses. The information allowed to assess the seismic vulnerability of the building aggregates and the expected damage scenarios through empirical methodologies. The city of Scarperia, founded a few kilometres from Florence during the Medieval Age and characterized by a medium seismicity, has been chosen as a case study for the presented procedure

Building Resilience in Times of New Global Challenges: A Focus on Six Main Attributes

This work discusses the crucial concept of resilience in six specific paragraphs, starting from the grid of the main attributes (namely, safety, robustness, adaptive capacity, sustainability, governance, and anamnesis) proposed by Indirli (2019). This study found that two views were particularly challenging, however conflicting: the homeostatic approach (engineering resilience, e.g. oscillations around an initial steady state) or the autopoietic approach (ecological resilience, e.g. irreversible shifts towards a new situation). In fact, a reliable resilience’s assessment is fundamental when geohazards affect the environment, urban habitat, building construction, lifelines and heritage. The reason of this study is also due to the increasing ambiguity whereby the term is frequently used in multidisciplinary fields, as engineering, social-economical/social-ecological systems and disaster/risk assessment in case of catastrophic scenarios. Therefore, considering the urgent need of analysis tools to prevent/properly govern future crises, the authors intend to give a useful hint towards the adoption of resilient approaches. The original and captivating methodology developed here confirms and enhances the validity of the starting point cornerstones (modifying and fulfilling the initial definitions), in primis the relationship between the resilience’s main concept and its attributes. Hence, the final goal is to provide an effective framework to study, without rigidity, complex questions in times of new global challenges, as the combination of natural and anthropogenic hazards, with particular reference to geohazards and global warming. Thus, successful actions focused on risk mitigation (with a tight link to communication, dissemination and exploitation policies) can be implemented, aimed at enhancing consciousness about disasters, for a wide range of different organizations, from experts in risk management and preservation of environment/heritage to people and stakeholders concerned. The investigation carried out here has been supported interlacing a theoretical discussion with the analysis of specific case studies (e.g. the behaviour of buildings, infrastructure and heritage under earthquakes and volcanic eruptions). It is to be noted that this approach has been already adopted to evaluate the overall resilience of the Italian community during the first period of the COVID-19 pandemic. Such a tragic event has certainly been a very hard test, where resilience should be considered as a strategic indicator, proving that really short time to operate effective choices is available, being the humanity able or not to govern the next changes, hopefully towards enough resilient results

Present and future resilience research driven by science and technology

Community resilience against major disasters is a multidisciplinary research field that garners an ever-increasing interest worldwide. This paper provides summaries of the discussions held on the subject matter and the research outcomes presented during the Second Resilience Workshop in Nanjing and Shanghai. It, thus, offers a community view of present work and future research directions identified by the workshop participants who hail from Asia – including China, Japan and Korea; Europe and the Americas

Exploring urban resilience to disasters : the role of planning in the long-term community rebuilding of Kalamata after the 1986 earthquake

Cette recherche explore la relation entre la planification, la reconstruction et la résilience, à travers l'analyse approfondie de la reconstruction à long terme d'une ville frappée par une catastrophe. Le but de cette recherche est de mieux comprendre le concept de résilience pour l'opérationnaliser. Premièrement, apporter une nouvelle perspective à la discussion sur la résilience en tant que concept théorique. Deuxièmement, contribuer à une nouvelle méthode d'évaluation pour explorer cette problématique, cette recherche utilise comme étude de cas une ville de taille moyenne qui a été frappée par une désastre. La ville de Kalamata, en Grèce, a été frappée par un tremblement de terre en Septembre 1986, ce qui l'a rendue dévastée. La trajectoire de développement de la ville à long terme offre une opportunité idéale pour explorer telles caractéristiques. Cette recherche examine les interventions et les pratiques de planification qui ont influencé les niveaux d'équilibre de la résilience de la ville au cours des périodes de pré-catastrophe et après la catastrophe et met l'accent sur l'interprétation des résultats dans le processus de récupération à long terme. Il se questionne si et comment les choix de planification influencent le rétablissement de la ville ainsi que sa résilience. La concentration sur la récupération à long terme est cruciale car elle révèle le succès ou l'échec du processus de récupération et elle vient compléter un vide dans la littérature étant donné que les études sont principalement concentrées sur les résultats de récupération à court terme. La résilience est un outil théorique largement répandu et en même temps largement contesté qui a été adopté par plusieurs domaines de recherche et utilisé différemment dans la plupart d'entre eux. Dans le domaine de la planification, la résilience est actuellement largement adoptée et est aujourd'hui un processus et un résultat très attendus dans la recherche et la pratique. La récupération à long terme et l'atténuation des risques sont les phases les moins explorées de la reconstruction post-catastrophe. Bien que beaucoup de recherches soient orientées vers les stratégies de réponse et de reconstruction, on accordera peu d'attention à la récupération à long terme et aux phases d'atténuation des dangers. L'innovation de cette recherche est qu'elle offre une nouvelle perspective en examinant comment la reconstruction a eu des impacts sur les lieux sur le long terme. Comment est-ce qu'ils ont amélioré leur résilience? Au lendemain d'un événement catastrophique, toutes les dynamiques sont mobilisées vers un soulagement et une reconstruction immédiats. Ces dynamiques restent malheureusement motivées pour un court terme après l'événement catastrophique. Bientôt la vie trouve un nouveau rythme et les signes de la catastrophe sont absorbés dans les besoins et les actes de la vie quotidienne. Cependant, les impacts des décisions prises après la catastrophe ne sont révélés qu'à long terme, pendant la phase de récupération à long terme. Pour que la reconstruction après sinistre soit couronnée de succès, une reconstruction résiliente à long terme est impérative. Au sein de cette recherche, la conceptualisation de la résilience est à la fois un défi et une nécessité afin de faire un premier pas vers la découverte de ce qui constitue une reconstruction résiliente à long terme post-catastrophe. Avec cette perspective à long terme, cette recherche explore la contribution des pratiques de planification à l'amélioration de l'équilibre de résilience d'une zone urbaine. Afin d'explorer à long terme la relation entre la planification et la résilience d'une communauté urbaine, un modèle d'évaluation de la résilience dans ce cadre spécifique est proposé. L'objectif est de donner une idée de la façon dont la planification peut affecter la résilience. Finalement, l’importance des pratiques de l'atténuation des risques et d’adaptation dans la planification est soulignée.This research explores the relationship between planning, reconstruction and resilience, through the in-depth analysis of the long-term recovery of a city hit by disaster. The purpose of this research is to further understand the concept of resilience in order to operationalize it. Firstly, to contribute a new perspective to resilience research as a theoretical concept. Secondly, to contribute to the operationalization of resilience with a new assessment method. To explore this problematic this research uses as case study a medium sized city that has been hit by a disaster in the past. The city of Kalamata, Greece was hit by an earthquake in September 1986, which left it devastated. The development trajectory of the city that is in an ongoing long-term recovery phase offers an ideal opportunity to explore such characteristics. This research examines the planning interventions and practices that have influenced the city’s resilience equilibrium levels during the pre-disaster and post-disaster periods and it focuses on the interpretation of the findings in the long-term recovery process. It questions if and how planning choices influence the recovery of the city as well as its resilience. The concentration on the long-term recovery is crucial as it reveals the success or fail of the recovery process and it comes to fill a void in literature given that studies are mostly concentrated on short-term recovery results. Resilience is already a widely popular and at the same time extensively contested theoretical concept that has been adopted by several fields of research and used differently in most of them. Within the field of planning resilience is currently being extensively adapted and is today a much-anticipated process and outcome of planning research and practice. Long-term recovery and hazard mitigation are the least explored phases of post disaster reconstruction. Although much research is orientated towards response and reconstruction strategies, little attention is given towards the long-term recovery and the hazard mitigation phases. The innovation of this research is that it offers a new perspective by examining how reconstruction has impacted places over the long term. How they have improved their resilience? In the aftermath of a catastrophic event, all dynamics are immediately mobilized towards immediate relief and reconstruction. These dynamics unfortunately remain motivated for only a short term after the catastrophic event. Soon life finds a new rhythm and the signs of the catastrophe are absorbed into the needs and deeds of everyday life. However, the impacts of the decisions taken shortly after the disaster are only revealed on the long term, during the long-term recovery phase. For disaster recovery to be successful, a long term resilient rebuilding vision is imperative. Within this research, the conceptualization of resilience is both a challenge and a necessity to take a first step towards the outlining of what constitutes a long-term resilient post-disaster community rebuilding. With this long-term perspective, this research explores the contribution of planning practices towards the amelioration of the resilience equilibrium of an urban area. To analyze the relationship between planning and resilience of an urban community on the long term, a model for assessing resilience within this specific framework is created. The objective is to give an insight in the ways planning can affect resilience. In this way, the importance of hazard mitigation and adaptation in the field of planning is highlighted

Multi-risk assessment in a historical city

AbstractNatural hazards pose a significant threat to historical cities which have an authentic and universal value for mankind. This study aims at codifying a multi-risk workflow for seismic and flood hazards, for site-scale applications in historical cities, which provides the Average Annual Loss for buildings within a coherent multi-exposure and multi-vulnerability framework. The proposed methodology includes a multi-risk correlation and joint probability analysis to identify the role of urban development in re-shaping risk components in historical contexts. The workflow is unified by exposure modelling which adopts the same assumptions and parameters. Seismic vulnerability is modelled through an empirical approach by assigning to each building a vulnerability value depending on the European Macroseismic Scale (EMS-98) and modifiers available in literature. Flood vulnerability is modelled by means of stage-damage curves developed for the study area and validated against ex-post damage claims. The method is applied to the city centre of Florence (Italy) listed as UNESCO World Heritage site since 1982. Direct multi-hazard, multi-vulnerability losses are modelled for four probabilistic scenarios. A multi-risk of 3.15 M€/year is estimated for the current situation. In case of adoption of local mitigation measures like floodproofing of basements and installation of steel tie rods, multi-risk reduces to 1.55 M€/yr. The analysis of multi-risk correlation and joint probability distribution shows that the historical evolution of the city centre, from the roman castrum followed by rebuilding in the Middle Ages, the late XIX century and the post WWII, has significantly affected multi-risk in the area. Three identified portions of the study area with a different multi-risk spatial probability distribution highlight that the urban development of the historical city influenced the flood hazard and the seismic vulnerability. The presented multi-risk workflow could be applied to other historical cities and further extended to other natural hazards