On assessing importance of components in dysfunction urban systems given an earthquake: the case of Mt. Etna region (original) (raw)
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Disruption index, DI: an approach for assessing seismic risk in urban systems (theoretical aspects)
Bulletin of Earthquake Engineering, 2014
Urban systems are characterized by very complex interactions. After an earthquake, a wide variety of services, networks and urban facilities may be unavailable to the public during the system failure and recovery processes, thereby causing disruptions in the basic social needs of the affected area. After a disaster, communities face several challenges. For example, the lack of education may impose population migrations, or malfunctions in the electricity distribution system can produce electrical power outages of varying duration with respect to time and space, which generates consequences in the water distribution system, transportation, communications, etc. A methodology called the Disruption index (DI), based on graph theory, includes these multiple interdependencies. It has been developed to estimate the dysfunction of some fundamental dimensions of urban systems on a broad level, starting with the physical damages directly suffered by the exposed assets, proceeding to the impacts that each node has on the functional performance of the nodes depending on them, until reaching the top node. This paper presents the fundamental theory to support the DI concept. The DI provides the likely impacts and consequences of an earthquake in an urban area to fulfill hazard mitigation and provide civil protection agencies and local and state governments with a new decision-making instrument to reduce or prevent severe and recurrent impacts. The DI concept can also be extended to other natural and man-made disasters and may be used as a tool for optimizing the resources of the system components. Keywords Seismic risk • Interdependencies • Propagation • Disruption • Urban systems 1 Introduction A few short minutes may be all it takes to destroy not only lives but also schools, homes and livelihoods.
Bulletin of Earthquake Engineering, 2015
A procedure for seismic risk assessment is applied to the Mt. Etna area (eastern Sicily, Italy) through assessment of urban system dysfunction following the occurrence of an earthquake. The tool used is based on the Disruption Index as a concept implemented in Simulator QuakeIST, which defines urban disruption following a natural disaster. The first element of the procedure is the definition of the seismic input, which is based on information about historical seismicity and seismogenic faults. The second element is computation of seismic impact on the building stock and infrastructure in the area considered. Information on urban-scale vulnerability was collected and a geographic information system was used to organise the data relating to buildings and network systems (e.g., building stock, schools, strategic structures, lifelines). The central idea underlying the definition of the Disruption Index is identification and evaluation of the impact on a target community through the physical elements that most contribute to severe disruption. The procedure applied in this study (i.e., software and data) constitutes a very useful operational tool to drive the development of strategies to minimise risks from earthquakes. Keywords Seismic impact Á Disruption Index Á Urban system Á Risk measures Á Mt. Etna area (Italy)
Engineering Geology for Society and Territory - Volume 5, 2014
The Disruption Index is used here for the assessment of urban disruption in the Mt. Etna area after a natural disaster. The first element of the procedure is the definition of the seismic input, which is based on information about the historical seismicity and seismogenic faults. The second element is the computation of the seismic impact on the building stock and infrastructure in the region considered. Information on urban-scale vulnerability was collected and a geographic information system was used to organize the data relating to buildings and network systems (e. g., typologies, schools, strategic structures, lifelines). The central idea underlying the definition of the Disruption Index is the identification and evaluation of the impacts on a target community, considering the physical elements that contribute most to the severe disruption. The results of this study are therefore very useful for earthquake preparedness planning and for the development of strategies to minimize the risks from earthquakes. This study is a product of the European "Urban Disaster Prevention Strategies using Macroseismic Fields and Fault Sources" project (UPStrat-MAFA European project 2013).
2012
SUMMARY This paper presents the ongoing activities for the assessment of the urban seismic risk at Mt. Etna volcano using the “Disruption Index” approach. We use updated information on the historic main seismicity, seismogenic faults and intensity attenuation that in a recent research project produced probabilistic seismic hazard maps and scenarios expressed in terms of macroseismic intensity. To apply the Disruption Index at Etna, we consider a probabilistic approach for seismic hazard evaluation based jointly on macroseismic fields and fault parameters. For information on the urban scale vulnerability, we use a GIS to organise data relating to buildings and network systems (e.g. typologies, schools, strategic structures, lifelines) related to the municipalities more exposed to seismic risk. The convolution of ground motion and vulnerability/ impact is based on a Monte Carlo simulation. We present here some preliminary results on the identification of nodes that are responsible for...
Bulletin of Earthquake Engineering, 2022
This paper presents a novel hybrid-based methodology devoted to develop urban fragility curves and damage probability matrices to predict likelihood seismic damage scenarios for small and medium Italian urban centres, considering URM buildings only. The concept of urban fragility curve consists of a single curve mean-representative of the seismic fragility of an entire area accounting for the combinations of building classes and their percentage, then they differ from those typological. The methodology has been developed with reference to Rocca di Mezzo, a small Italian urban centre located in the central Apennine area, Italy. Based on CarTiS inventory, building classes have been firstly recognized and urban fragility curves, representative for damage scenarios at Ultimate Limit State, developed. To predict damage scenarios from low to high-intensity earthquakes, an approach to define multi-damage urban fragility curves and damage probability matrices has been also presented. To this aim, a damage scale suffered by building classes has been defined by converting the final outcomes of the AeDES form (used in Italy for post-earthquake surveys) in the damage levels provided by the European Macroseismic Scale (EMS98). Data coming from urban fragility curves have been compared with the actual damage scenario recorded in Rocca di Mezzo after the 2009 L'Aquila's earthquake, in terms of both peak-ground acceleration and Mecalli-Cancani-Sieberg scale. The achieved results showed a good accordance between theoretical predictions and actual damage scenarios, coherent also with the damage scenarios occurred in other Italian historical centres hit by severe earthquakes over the years. Thus, the methodology can provide a first important indicator to support the development of emergently plans devoted to identify priority of interventions in such areas particularly vulnerable with respect to others.
Vulnerability of Building, urban infrastructure and system: The case of Mt. Etna
2014
Natural disasters, such as earthquakes and volcanoes, have strong effects on the socio-economic wellbeing of countries and their people. The consequences of these events can lead to complex cascades of related incidents; when these expand across sectors and borders, and in more serious contexts, they can threaten our basic survivability. These events have clearly demonstrated that preparedness and disaster management is a dynamic process that requires a holistic analysis of critical interdependencies among core infrastructures. In this context of complexity, uncertainty and doubt, the Disruption Index (DI) proposed in the framework of the UPStrat-MAFA project aims to improve our understanding of earthquake and volcano hazards and their impacts. Several guiding principles and methods have been developed to serve as the basis to measure the different earthquake impacts, with analysis and discussion of the data that provide clearer pictures of how the systems and the disruption of thei...
The Disruption Index (DI) as a tool to measure disaster mitigation strategies
Bulletin of Earthquake Engineering, 2015
Apart from the loss of lives, injuries and homeless resulting from an earthquake, not only the economy and physical landscape are altered, but also the lives of citizens and their places of work are dramatically altered. If critical services and functions are disrupted for more than a reasonable time period, consequences can be severe. All communities are at risk and face potential disaster, if unprepared. The Disruption Index (DI) is a tool that allows the representation of a complex and multidimensional situation in a concise and easier way, providing institutions and communities with a way to identify the global earthquake impact in a geographical area, the elements at risk, and the means to reduce it. In the present paper, after a short review of the concept of DI, its geographic (spatial) distribution is developed and an application to some cities in Algarve (Portugal) is made. Then, the use of DI in the context of measuring the risk reduction for alternative disaster mitigation strategies is introduced and illustrations are presented.
Bulletin of Earthquake Engineering, 2011
The earthquake that struck Faial, Pico and São Jorge in 1998 has allowed the collection of an unprecedented quantity of good-quality data on damage to construction, costs of repair and other variables. A general overview of the impact of the earthquake is presented, and its effects on the population, housing, monumental structures and economy 10 years after its occurrence are analysed and briefly reported in this paper. We present the overall results obtained from multiple sources of information, primarily from an integrated database containing all the data gathered. The results that describe the inflicted damage, costs of repair and other variables are presented both statistically and geographically. This information was valuable for the construction of an overall earthquake impact based on the systemic analysis of the urban area through the identification of criteria and definition of descriptors leading to a disruption index. The paper is developed as follows. First, we introduce the descriptions of the earthquake effects on the broader set of existing urban systems. In the second part we present the main methodological aspects leading to the disruption index, as well as analysing and discussing the data to provide a clearer picture of how the analysed systems and their disruption affect an urban area.
Dimensions of Earthquake Disaster in Urban Areas
In disaster management, earthquakes are one of the leading causes of death. The aftermath of such phenomena can be abated if proper actions take place before the onset of the earthquake. Various sectors in a country are responsible for managing earthquakes but lack of knowledge about the positive effects of their actions makes them reluctant to do so. Stabilizing houses and structures, positioning humanitarian goods, retrofitting transportation links, and devising a disaster response plan can help save more lives. Of course, these actions are separate projects with defined budgets which are assigned to different sectors, but coordination of them is necessary. To highlight the effects of pre-disaster actions on recovery costs, Recovery Indexes are introduced which show the state of the city after the earthquake. Also a model is proposed to calculate the recovery costs of an earthquake when different actions have taken place. The results show how significant any pre-disaster action can be on the recovery cost and the essentiality of taking actions before it is too late.