A three-level framework for multi-risk assessment

The effective management of the risks posed by natural and man-made hazards requires all relevant threats and their interactions to be considered. This paper proposes a three-level framework for multi-risk assessment that accounts for possible hazard and risk interactions. The first level is a flow chart that guides the user in deciding whether a multi-hazard and risk approach is required. The second level is a semi-quantitative approach to explore if a more detailed, quantitative assessment is needed. The third level is a detailed quantitative multi-risk analysis based on Bayesian networks. Examples that demonstrate the application of the method are presented.     

Megacities and natural disasters: a comparative analysis*

Natural disasters are a worsening problem in many of the world's largest cities. Since an increasing majority of the world's population will soon live in cities, and mostly in large cities, the trend towards increasing urban hazard poses serious societal challenges for the future. Beginning in the mid-1990s, the International Geographical Union's Study Group on the Disaster Vulnerability of Megacities undertook a series of case studies of megacities that have been – and are – exposed to major natural disasters. These include: Tokyo, Seoul, Sydney, Lima, Mexico City, Los Angeles, San Francisco, Miami, London and Dhaka. Case studies focused on reviewing the historic record of major disasters in each city and on documenting recent changes in different components of hazard including, risk, exposure, vulnerability and response. It was found that exposure and vulnerability are the components of hazard that are changing fastest and with the gravest implications for urban populations. Because hazards are only one part of the typical urban management agenda, hazards management in large cities should be pursued with careful regard to the context of general urban policy manking and management. Sustainability has become a guiding principle of urban management but the relationship between hazard and sustainability is little understood and little explored. The way lies open for hazard researchers to develop alternative contextualized approaches to the analysis and resolution of urban hazard issues. This revised version was published online in July 2006 with corrections to the Cover Date.     

A multi-component flood risk assessment in the Maresme coast (NW Mediterranean)

Coastal regions are the areas most threatened by natural hazards, with floods being the most frequent and significant threat in terms of their induced impacts, and therefore, any management scheme requires their evaluation. In coastal areas, flooding is a hazard associated with various processes acting at different scales: coastal storms, flash floods, and sea level rise (SLR). In order to address the problem as a whole, this study presents a methodology to undertake a preliminary integrated risk assessment that determines the magnitude of the different flood processes (flash flood, marine storm, SLR) and their associated consequences, taking into account their temporal and spatial scales. The risk is quantified using specific indicators to assess the magnitude of the hazard (for each component) and the consequences in a common scale. This allows for a robust comparison of the spatial risk distribution along the coast in order to identify both the areas at greatest risk and the risk components that have the greatest impact. This methodology is applied on the Maresme coast (NW Mediterranean, Spain), which can be considered representative of developed areas of the Spanish Mediterranean coast. The results obtained characterise this coastline as an area of relatively low overall risk, although some hot spots have been identified with high-risk values, with flash flooding being the principal risk process.     

Economic risk maps of floods and earthquakes for European regions

Europe experiences different natural hazards and subsequent risks that have various effects on the development of its regions. The spatial significance of hazards can be expressed as an economic risk when combining hazard potential with vulnerability data. Two examples of European natural hazard maps on floods and earthquakes, as well as the resulting risk profiles of regions (combination of hazard potential and vulnerability) give a first impression on the spatial characters of hazards in Europe and their potential impact on further spatial development. The economic risk maps enable a view on the spatial dimension of the economic damage potential of flood and earthquakes, pointing out comparable situations across Europe with the aim to facilitate targeted responses and policies. The spatial character of a hazard is either defined by spatial effects that might occur in case of a disaster or by the possibility of spatial planning responses. The integration of the economic vulnerability of a region (regional GDP per capita, population density) leads to a classification of areas according to their economic risk or damage potential towards hazards. These synthetic risk profiles are presented as risk maps of European regions in administrative boundaries. Obtained information can be of interest for spatial planning and development strategies, e.g. economic risk profile of regions can influence the targets of investments and could thus be an important background for structural funding.     

冰湖溃决灾害风险研究进展及其展望

系统回顾了国内外冰湖溃决灾害风险研究现状,结果显示,以往冰湖溃决灾害风险评估研究过多集中于冰湖溃决致灾诱因、特征,溃决危险性评价和溃决概率预测以及溃决洪峰流量及其演进模拟研究等自然风险方面,而承灾区经济社会系统脆弱性、暴露性和适应性风险研究却较为缺乏。因此,开展冰湖溃决灾害综合风险研究,不仅对冰湖溃决危险性评价意义重大,而且对于下游承灾区防灾减灾和预警体系建立也具有重要的理论参考价值。     

Integrated risk assessment of multi-hazards in China

Maps of population exposure, vulnerability and risk to natural hazards are useful tools for designing and implementing disaster risk mitigation programs in China. The ranking of provinces by relative risk to natural hazards would provide a metric for prioritizing risk management strategies. Using provinces as our study unit, from the perspectives of hazard exposure, susceptibility, coping capacity and adaptive capacity, this study first constructed China’s disaster risk index for five types of major natural hazards: earthquakes, floods, droughts, low temperatures/snow and gale/hail. Then, the relative risk level at the provincial scale in China was assessed. Finally, the hotspots with the highest hazard exposure, vulnerability and risk were identified. The results showed that high exposure was a significant risk driver in China, whereas high vulnerability, especially social vulnerability, amplified the risk levels. Similar to the population exposure to disasters, the relative risk levels in the southwestern, central and northeastern regions of China were significantly higher than those in the eastern, northern and western regions. The high-risk regions or hotspots of multi-hazards were concentrated in southern China (less-developed regions), while the low-risk regions were mainly distributed in the eastern coastal areas (well-developed regions). Furthermore, a nonlinear relationship existed between the disaster risk level and poverty incidence as well as per capita GDP, demonstrating that disaster losses in middle-income areas are likely to increase if economic policies are not modified to account for the rising disaster risk. These findings further indicated that research on disaster risk should focus not only on hazards and exposure but also on the vulnerability to natural disasters. Thus, reducing vulnerability and population exposure to natural hazards would be an effective measure in mitigating the disaster risk at hotspots in China.     

Multilayer-exposure maps as a basis for a regional vulnerability assessment for landslides: applied in Waidhofen/Ybbs,Austria

Assessments of natural hazards and risks are beneficial for sustainable planning and natural hazard risk management. On a regional scale, quantitative hazard and risk assessments are data intensive and methods developed are difficult to transfer to other regions and to analyse different periods in a given region. Such transfers could be beneficial regarding factors of global change influencing the patterns of natural hazard and risk. The aim of this study was to show the landslide exposure of different elements at risk in one map, e.g. residential buildings and critical infrastructure, as a solid basis for an in-depth analysis of vulnerability and consequent risk. This enables to overcome the data intensive assessments on a regional scale and highlights the potential hotspots for risk analysis. The study area is located in the alpine foreland in Lower Austria and comprises around 112 km². The results show the different levels of exposure, as well as how many layers of elements at risk are affected. Several exposure hotspots can be delineated throughout the study area. This allows a decision on in-depth analysis of hotspots not only by indicated locations but also by a rank resulting from the different layers of incorporated elements at risk.     

Active faulting and natural hazards in Armenia, eastern Turkey and northwestern Iran

Active fault zones of Armenia, SE Turkey and NW Iran present a diverse set of interrelated natural hazards. Three regional case studies in this cross-border zone are examined to show how earthquakes interact with other hazards to increase the risk of natural disaster. In northern Armenia, a combination of several natural and man-made phenomena (earthquakes, landslides and unstable dams with toxic wastes) along the Pambak-Sevan-Sunik fault (PSSF) zone lowers from 0.4 to 0.2–0.3g the maximum permissible level (MPL) of seismic hazard that may induce disastrous destruction and loss of life in the adjacent Vanadzor depression.

In the Ararat depression, a large active fault-bounded pull-apart basin at the junction of borders of Armenia, Turkey, Iran and Azerbaijan, an earthquake in 1840 was accompanied by an eruption of Ararat Volcano, lahars, landslides, floods, soil subsidence and liquefaction. The case study demonstrates that natural hazards that are secondary with respect to earthquakes may considerably increase the damage and the casualties and increase the risk associated with the seismic impact.

The North Tabriz–Gailatu fault system poses a high seismic hazard to the border areas of NW Iran, eastern Turkey, Nakhichevan (Azerbaijan) and southern Armenia. Right-lateral strike–slip motions along the North Tabriz fault have given rise to strong earthquakes, which threaten the city of Tabriz with its population of 1.2 million.

The examples illustrate how the concentration of natural hazards in active fault zones increases the risk associated with strong earthquakes in Armenia, eastern Turkey and NW Iran. This generally occurs across the junctions of international borders. Hence, the transboundary character of active faults requires transboundary cooperation in the study and mitigation of the natural risk.     

The structural vulnerability in the framework of natural hazard risk analyses and the exemplary application for storm loss modelling in Tyrol (Austria)

In the context of natural hazard-related risk analyses, different concepts and comprehensions of the term risk exist. These differences are mostly subjected to the perceptions and historical backgrounds of the different scientific disciplines and results in a multitude of methodological concepts to analyse risk. The target-oriented selection and application of these concepts depend on the specific research object which is generally closely connected to the stakeholders’ interests. An obvious characteristic of the different conceptualizations is the immanent various comprehensions of vulnerability. As risk analyses from a natural scientific-technical background aim at estimating potential expositions and consequences of natural hazard events, the results can provide an appropriate decision basis for risk management strategies. Thereby, beside the preferably addressed gravitative and hydrological hazards, seismo-tectonical and especially meteorological hazard processes have been rarely considered within multi-risk analyses in an Alpine context. Hence, their comparative grading in an overall context of natural hazard risks is not quantitatively possible. The present paper focuses on both (1) the different concepts of the natural hazard risk and especially their specific expressions in the context of vulnerability and (2) the exemplary application of the natural scientific-technical risk concepts to analyse potential extreme storm losses in the Austrian Province of Tyrol. Following the corresponding general risk concept, the case study first defines the hazard potential, second estimates the exposures and damage potentials on the basis of an existing database of the stock of elements and values, and third analyses the so-called Extreme Scenario Losses (ESL) considering the structural vulnerability of the potentially affected elements at risk. Thereby, it can be shown that extreme storm events can induce losses solely to buildings and inventory in the range of EUR 100–150 million in Tyrol. However, in an overall context of potential extreme natural hazard events, the storm risk can be classified with a moderate risk potential in this province.     

Seismic Hazard Mitigation for Buildings

Recent natural hazards have exposed the dire consequence of damage and impact upon the built environment. It appears that one of the biggest challenges to the natural hazard mitigation community is how to improve the performance of older building and infrastructure to enhance their ability to withstand natural hazards. By improving their performance, the risk associated with buildings and infrastructure against natural hazards can be mitigated. Within the context of risk management of buildings against earthquakes, the general practice is to follow a three-step process, namely screening, evaluation and mitigation. Screening constitutes a preliminary evaluation process and sets priority for detailed evaluation. Evaluation compares a built environment with code requirements for new construction and sets priority for mitigation. Mitigation can be achieved by means of retrofit or replacement. Retrofit is intended to improve the performance of built environment as required. Replacement may be the only viable solution when economical, technical and environmental considerations are account for.     

Understanding the vulnerability of migrants in Shanghai to typhoons

China has experienced considerable migration from inland to coastal areas since the reforms of 1978, with migrants becoming an important population in many coastal cities. Compared with non-migrants (long-term residents), migrant vulnerability to typhoons is considered high due to limited access to job opportunities, social security, information, and other resources; however, there is no research on vulnerability of this population sector to natural hazards. This initial study analysed the perceptions and personal experiences of migrants living in Shanghai of typhoon hazards. During May 2010, empirical data were collected using an online questionnaire and face–face interviews. Response data indicated that risk knowledge of migrants was significantly lower than among non- migrants; differing risk perceptions between the groups were consistent with levels of personal typhoon experience; statistically significant differences in hazard knowledge within the sample also related to education and occupation; a variety of strategies to cope with typhoon hazards was being applied by residential committees; and that migrants were not generally recognised as a vulnerable group requiring special consideration in hazard risk management. To reduce the vulnerability of migrants to typhoons, we recommend expanding the range of accessible communication technologies distributing warning information; organising more educational and training programmes, at government and corporate level, to increase community awareness of natural hazards; encouraging local residential committees to promote social networks and engagement for migrants; and providing corporate incentives to develop insurances specifically for migrant needs. Further research is necessary to assess the differences in vulnerability between different types of migrants.     

Is there a tolerable level of risk from natural hazards in New Zealand?

Following the 2010 and 2011 earthquake and aftershocks in Canterbury, New Zealand, extensive research was carried out on the rockfall hazard to residential buildings on Christchurch's Port Hills. To determine which dwellings faced an unacceptable risk to life safety, the recommendation was made to adopt a tolerable threshold for individual risk of 1/10,000 p.a. (10^?4 p.a.). The 10^?4 p.a. threshold has subsequently been considered for application to other natural hazards. However, this threshold is far too high. It is about 35 times higher than the post-colonial historic average for natural hazards, it is 100 times greater than New Zealand's structural design standard for new buildings and it is 10–100 times greater than the risk tolerated by comparable jurisdictions for existing and new risks, respectively. A more appropriate threshold for the risk from natural hazards is within the range from 10^?5 p.a. for existing exposure to 10^?6 p.a. for new exposure. The reason for adopting this arbitrarily high threshold for rock roll hazard appeared to be to balance an overestimation of calculated risk given the large uncertainties inherent in the data. However, there are some concerns if this acceptance criterion is applied to other natural hazards where underlying risk might be more accurately estimated.     

The role of coupling and embeddedness in risk evolution: rethinking the snow event in early 2008, China

New forms of hazards generated by extreme weather pose new challenges to emergency management. The purpose of this paper is to identify a typical evolution dynamics by analyzing coupling and embeddedness in risk evolution via critical infrastructure system under extreme weather. Evidence from the snow event in early 2008, China, is used to draw the viewpoint and support the argument. The paper identifies the dynamics that how a natural hazard of extreme weather evolves into a social crisis and how coupling and embeddedness contribute to the evolution. This paper makes it evident that the impact of natural hazard to a society can obtain amplification through coupling and embeddedness. Therefore, new challenges in risk evolution should become a highlighted direction for further research. This paper sheds light on a new profile for social impact research of natural hazard and provides new insights into systems thinking on emergency management.     

A review of multiple natural hazards and risks in Germany

Although Germany is not among the most hazard-prone regions of the world, it does experience various natural hazards that have caused considerable economic and human losses in the past. Moreover, risk due to natural hazards is expected to increase in several regions of Germany if efficient risk management is not able to accommodate global changes. The most important natural hazards, in terms of past human and economic damage they caused, are storms, floods, extreme temperatures and earthquakes. They all show a pronounced spatial and temporal variability. In the present article, a review of these natural hazards, associated risks and their management in Germany is provided. This review reveals that event and risk analyses, as well as risk management, predominantly focus on one single hazard, generally not considering the cascading and conjoint effects in a full multi-hazard and risks approach. However, risk management would need integrated multi-risk analyses to identify, understand, quantify and compare different natural hazards and their impacts, as well as their interactions.     

Editorial

The Far North Queensland city of Cairns has a significant history of exposureto the impact of a wide range of natural hazards, most notably tropical cyclones.A program of publicly funded research, using Cairns as its `living laboratory'and aimed at understanding the risks posed by these hazards was a central partof Australia's involvement in the International Decade for Natural DisasterReduction. This program involved input from all three levels of governmentin Australia – national, state and local – as well as academe, industry and the Cairns community.This paper outlines the background to this program of research and an overview ofthe Cairns community that provides context for the other papers in this issue. Whilemuch of the scientific effort has been focused on developing a better understandingof the hazard phenomena involved, an important outcome of the Cairns research hasbeen the evolution of techniques by which to develop a better understanding of thecommunity at risk and strategies by which to reduce their risk.     

Database of geo-hydrological disasters for civil protection purposes

This paper presents the results of a research concerning available historical information about natural hazards (landslides and floods) and consequent disasters in the Consortium of Mountain Municipalities of Valtellina di Tirano, in Northern Italy. A geo-referenced database, collecting information till 2008, was designed with the aim of using available data of historical events for hazard estimation and the definition of risk scenarios as a basis for Civil Protection planning and emergency management purposes. This database and related statistics about landslides and floods are shown, and a brief overview of historical disasters caused by natural hazards in the study area is presented. A case study showing how useful the database can be to define a simple but realistic scenario is described. Information availability and reliability is discussed and possible uncertainties are underlined. The study shows that collecting and making use of historical information for the definition of hypothetical scenarios and the evaluation of territorial threats is a fundamental source of knowledge to deal with future emergencies.     

Estimation of volcanic hazards based on Cox stochastic processes

Assessments of the probability and the consequences of future volcanic activity can be critical aspects when evaluating the safety of the population and of industrial plants. A new methodology has been developed for the probabilistic modelling of volcanic hazards based on regional volcanic data that facilitates the production of probabilistic hazard maps for various volcanic scenarios (lava flows, tephra). The stochastic model is based on Cox processes and allows account to be taken of the observed temporal and spatial correlation inherent in volcanic eruptions. The model is applied to the Quaternary field of the Osteifel region where the forecast number of future eruptions and the probabilities related to the different scenarios are estimated using a Monte Carlo approach. The obtained hazard maps of future volcanic events are part of a comprehensive hazard analysis and serve as a major input for the risk analysis that will determine the consequences of forecast volcanic activity at the site.     

Visualization of uncertainty in natural hazards assessments using an interactive cartographic information system

Natural hazard assessments are always subject to uncertainties due to missing knowledge about the complexity of hazardous processes as well as their natural variability. Decision-makers in the field of natural hazard management need to understand the concept, components, sources, and implications of existing uncertainties in order to reach informed and transparent decisions. Until now, however, only few hazard maps include uncertainty visualizations which would be much needed for an enhanced communication among experts and decision-makers in order to make informed decisions possible. In this paper, an analysis of how uncertainty is currently treated and communicated by Swiss natural hazards experts is presented. The conducted expert survey confirmed that the communication of uncertainty has to be enhanced, possibly with the help of uncertainty visualizations. However, in order to visualize the spatial characteristics of uncertainty, existing uncertainties need to be quantified. This challenge is addressed by the exemplary simulation of a snow avalanche event using a deterministic model and quantified uncertainties with a sensitivity analysis. Suitable visualization methods for the resulting spatial variability of the uncertainties are suggested, and the advantages and disadvantages of their implementation in an interactive cartographic information system are discussed.     

A method for na-tech risk assessment as supporting tool for land use planning mitigation strategies

Hazardous industrial sites have always represented a threat for the community often provoking major accidents overcoming the boundaries of the plants and affecting the surrounding urban areas. If the industrial sites are located in natural hazard-prone areas, technological accidents may be triggered by natural events, generating so-called na-tech events which may modify and increase the impact and the overall damage in the areas around them. Nevertheless, natural and technological hazards are still treated as two separate issues, and up to now the methods for na-tech risk assessment have been developed mainly for specific natural hazards, generally restricted to some plant typologies and to the area of the plant itself. Based on a review of the current na-tech literature, this article illustrates a risk assessment method as a supporting tool for land use planning strategies aimed at reducing na-tech risk in urban areas. More specifically, a multi attribute decision-making method, combined with fuzzy techniques, has been developed. The method allows planners to take into account, according to different territorial units, all the individual na-tech risk factors, measured through both quantitative and qualitative parameters, while providing them with a na-tech risk index, useful to rank the territorial units and to single out the priority intervention areas. The method is designed to process information generally available about hazardous plants (safety reports), natural hazards (hazard maps) and features of urban systems mainly influencing their exposure and vulnerability to na-tech events (common statistical territorial data). Furthermore, the method implemented into a GIS framework should easily provide planners with comparable maps to figure out the hazard factors and the main territorial features influencing the exposure and vulnerability of urban systems to na-tech events. The method has been tested on a middle-sized Municipality in the Campania Region, identified as 2nd class seismic zone, according to the Ordinance 3274/2003, in which a LPG storage plant, classified as a plant with major accident potential by the Seveso II Directive (art. 9), is located just within the city core.     

Natural hazards in Central Java Province,Indonesia: an overview

Central Java Province, Indonesia, suffers from natural hazard processes such as land subsidence, coastal inundation, flood, volcanic eruption, earthquake, tsunami, and landslide. The occurrence of each kind of natural hazard is varied according to the intensity of geo-processes. It is necessary to learn from the historical record of coastal inundation, flood, volcanic eruption, earthquake, tsunami, and landslide hazards in Central Java Province to address issues of comprehensive hazard mitigation and management action. Through the understanding about the nature and spatial distribution of natural hazards, treatments can be done to reduce the risks. This paper presents the natural hazard phenomena in Central Java Province and provides critical information for hazard mitigation and reduction.