Assessing building vulnerability to earthquake and tsunami hazard using remotely sensed data

Quantification of building vulnerability to earthquake and tsunami hazards is a key component for the implementation of structural mitigation strategies fostering the essential shift from post-disaster crisis reaction to preventive measures. Facing accelerating urban sprawl and rapid structural change in modern urban agglomerations in areas of high seismic and tsunami risk, the synergetic use of remote sensing and civil engineering methods offers a great potential to assess building structures up-to-date and area-wide. This paper provides a new methodology contextualizing key components in quantifying building vulnerability with regard to sequenced effects of seismic and tsunami impact. The study was carried out in Cilacap, a coastal City in Central Java, Indonesia. Central is the identification of significant correlations between building characteristics, easily detectable by remote sensing techniques, and detailed in situ measurements stating precise building vulnerability information. As a result, potential vertical evacuation shelters in the study area are detected and a realistic vulnerability assessment of the exposed building stock is given. These findings obtained allow for prioritization of intervention measures such as awareness and preparedness strategies and can be implemented in local disaster management.     

Spatiotemporal dynamics: the need for an innovative approach in mountain hazard risk management

Starting with an overview on losses due to mountain hazards in the Russian Federation and the European Alps, the question is raised why a substantial number of events still are recorded—despite considerable efforts in hazard mitigation and risk reduction. The main reason for this paradox lies in a missing dynamic risk-based approach, and it is shown that these dynamics have different roots: firstly, neglecting climate change and systems dynamics, the development of hazard scenarios is based on the static approach of design events. Secondly, due to economic development and population dynamics, the elements at risk exposed are subject to spatial and temporal changes. These issues are discussed with respect to temporal and spatial demands. As a result, it is shown how risk is dynamic on a long-term and short-term scale, which has to be acknowledged in the risk concept if this concept is targeted at a sustainable development of mountain regions. A conceptual model is presented that can be used for dynamical risk assessment, and it is shown by different management strategies how this model may be converted into practice. Furthermore, the interconnectedness and interaction between hazard and risk are addressed in order to enhance prevention, the level of protection and the degree of preparedness.     

延安宝塔山景区滑坡地质灾害风险评估

滑坡灾害易损性可分为两大类型:人口易损性和经济易损性。本文依据现场风险填图对宝塔山景区影响居民生命和财产安全的地质灾害进行了风险源的识别,认为宝塔山景区的风险源主要为潜在的滑坡及崩塌灾害,最大风险处人员伤亡总概率为2.6210-2a-1;同时,依据工程地质经验法对风险管理易损性各要素进行了定量评价,认为对宝塔山景区居民来说,100a以内居民平均每年有最大2.62%伤亡的概率存在。根据国际较通用的风险容许标准,认为目前部分宝塔山居民遭受的风险处于不可接受区,建议加强监测。     

Physical vulnerability assessment for alpine hazards: state of the art and future needs

Mountain hazards such as landslides, floods and avalanches pose a serious threat to human lives and development and can cause considerable damage to lifelines, critical infrastructure, agricultural lands, housing, public and private infrastructure and assets. The assessment of the vulnerability of the built environment to these hazards is a topic that is growing in importance due to climate change impacts. A proper understanding of vulnerability will lead to more effective risk assessment, emergency management and to the development of mitigation and preparedness activities all of which are designed to reduce the loss of life and economic costs. In this study, we are reviewing existing methods for vulnerability assessment related to mountain hazards. By analysing the existing approaches, we identify difficulties in their implementation (data availability, time consumption) and differences between them regarding their scale, the consideration of the hazardous phenomenon and its properties, the consideration of important vulnerability indicators and the use of technology such as GIS and remote sensing. Finally, based on these observations, we identify the future needs in the field of vulnerability assessment that include the user-friendliness of the method, the selection of all the relevant indicators, the transferability of the method, the inclusion of information concerning the hazard itself, the use of technology (GIS) and the provision of products such as vulnerability maps and the consideration of the temporal pattern of vulnerability.     

Quantitative multi-risk analysis for natural hazards: a framework for multi-risk modelling

This paper introduces a generic framework for multi-risk modelling developed in the project ‘Regional RiskScape’ by the Research Organizations GNS Science and the National Institute of Water and Atmospheric Research Ltd. (NIWA) in New Zealand. Our goal was to develop a generic technology for modelling risks from different natural hazards and for various elements at risk. The technical framework is not dependent on the specific nature of the individual hazard nor the vulnerability and the type of the individual assets. Based on this generic framework, a software prototype has been developed, which is capable of ‘plugging in’ various natural hazards and assets without reconfiguring or adapting the generic software framework. To achieve that, we developed a set of standards for treating the fundamental components of a risk model: hazards, assets (elements at risk) and vulnerability models (or fragility functions). Thus, the developed prototype system is able to accommodate any hazard, asset or fragility model, which is provided to the system according to that standard. The software prototype was tested by modelling earthquake, volcanic ashfall, flood, wind, and tsunami risks for several urban centres and small communities in New Zealand.     

Risk-based damage potential and loss estimation of earthquake scenarios in the moderate endangered Austrian Federal Province of Tyrol

Although geophysical hazards like earthquakes can lead to tremendous losses, they are often neglected or not considered in risk analyses within an Alpine context. However, lately and especially in the framework of multi-risk analyses, earthquake risk studies are being increasingly implemented within an Alpine relation too. The presented study was conducted to quantitatively estimate potential consequences of earthquake events in the Austrian Province of Tyrol. The methodological study framework integrates the general risk components (i) hazard, (ii) elements at risk, and (iii) vulnerability. They are considered on a regional scale, accepting pragmatic approaches with simplified procedures and assumptions. Scenarios for different potential epicentres were calculated based on two different macroseismic hazard maps derived from punctual ground motion values of the building code and microzonation studies. The maps take into account the design event definitions of existing building code and a, thereupon based, simple and mono-causal Maximum Credible Earthquake assumption. Corresponding elements at risk and damage potentials were identified and potential losses were estimated under consideration of different vulnerability approaches. It can be shown that most scenarios based on the design event definition of the Austrian and European building codes, respectively have the potential of building and inventory losses solely of some hundred million up to approximately €4 billion. Additional, building and inventory losses of maximum credible events can lead to losses of more than €7 billion merely in connection with the primary earthquake event neglecting all other cascading effects.     

A quantitative vulnerability function for fluvial sediment transport

In quantitative risk assessment, risk is expressed as a function of hazard, elements at risk exposed, and vulnerability. Vulnerability is defined as the expected degree of loss for an element at risk as a consequence of a certain event, following a natural-scientific approach combined with economic methods of loss appraisal. The resulting value ranges from 0 (no damage) to 1 (complete destruction). With respect to torrent processes, i.e., fluvial sediment transport, this concept of vulnerability—though widely acknowledged—did not result in sound quantitative relationships between process intensities and associated degrees of loss so far, even if considerable loss occurred during recent years. To close this gap and establish this relationship, data from three well-documented torrent events in the Austrian Alps were used to derive a quantitative vulnerability function applicable to residential buildings located on torrent fans. The method applied followed a spatially explicit empirical approach within a GIS environment and was based on process intensities, the spatial characteristics of elements at risk, and average reconstruction values on a local scale. Additionally, loss data were collected from responsible administrative bodies and analysed on an object level. The results suggest a modified Weibull distribution to fit best to the observed damage pattern if intensity is quantified in absolute values, and a modified Frechet distribution if intensity is quantified relatively in relation to the individual building height. Additionally, uncertainties resulting from such an empirical approach were studied; in relation to the data quality a 90% confidence band was found to represent the data range appropriately. The vulnerability relationship obtained allows for an enhanced quantification of torrent risk, but also for an inclusion in comprehensive vulnerability models including physical, social, economic, and institutional vulnerability. As a result, vulnerability to mountain hazards might decrease in the future.     

Mountain Protection Forests against Natural Hazards and Risks: New French Developments by Integrating Forests in Risk Zoning

Forests can play a very significant role in protection against natural hazards and risks in mountain lands, especially against erosion and rockfalls. This paper first assesses knowledge concerning the capacity of forests to control natural hazards, with emphasis placed on forest location in catchments or slopes. Zoning aspects are then presented; based on the use of GIS, they allow determining priorities for forestry operations (cuts and biological engineering), in view to setting up an 'optimal management' of mountain forest ecosystems. Finally, an explanation is given of how the results of research are used for the management and planning of mountain ecosystems, illustrated by an example of researcher-practitioner transfer in France. Zoning, prevention, display and regular aspects are developed. On the basis of the experience and knowledge presented here, recommendations are proposed to better take into account the role of mountain forests in the control of natural hazards and risks. It is necessary to have an adapted legislative and economic framework, define priority forest intervention zones and determine an adapted sylviculture.     

澜沧江流域重大水电工程扰动灾害风险评价

地质灾害风险性评价对当地防灾减灾具有指导意义。本文以澜沧江重大水电工程扰动灾害为例,在遥感解译与野外实际调查的基础上,选取高程、坡度、坡向、植被归一化指数、距库区距离、工程地质岩组、断裂带密度、年均降雨量、地震峰值加速度9个因素,并基于加权信息量模型进行危险性评价,然后以人口密度、水电站、道路、土地覆盖类型和GDP为承灾体进行易损性评价,最后将危险性和易损性进行信息融合,构建地质灾害风险性矩阵,完成地质灾害风险性评价。评价结果表明:极高和高风险区主要分布在乌弄龙及其上游水电站附近,以及下游库区两岸人类活动相对密集区域,中风险区主要分布在乌弄龙上游库区两岸以及乌弄龙—托巴水电站全域,在下游零散分布;低风险区主要分布在中游高山峡谷段。本次研究较为准确地评估了地质灾害风险性,可为澜沧江流域扰动地质灾害风险规划提供科学依据和技术指导。     

Spatial scan statistics in vulnerability assessment: an application to mountain hazards

In the European Alps, the concept of risk has increasingly been applied in order to reduce the susceptibility of society to mountain hazards. Risk is defined as a function of the magnitude and frequency of a hazard process times consequences; the latter being quantified by the value of elements at risk exposed and their vulnerability. Vulnerability is defined by the degree of loss to a given element at risk resulting from the impact of a natural hazard. Recent empirical studies suggested a dependency of the degree of loss on the hazard impact, and respective vulnerability (or damage-loss) functions were developed. However, until now, only little information is available on the spatial characteristics of vulnerability on a local scale; considerable ranges in the loss ratio for medium process intensities only provide a hint that there might be mutual reasons for lower or higher loss rates. In this paper, we therefore focus on the spatial dimension of vulnerability by searching for spatial clusters in the damage ratio of elements at risk exposed. By using the software SaTScan, we applied an ordinal data model and a normal data model in order to detect spatial distribution patterns of five individual torrent events in Austria. For both models, we detected some significant clusters of high damage ratios, and consequently high vulnerability. Moreover, secondary clusters of high and low values were found. Based on our results, the assumption that lower process intensities result in lower damage ratios, and therefore in lower vulnerability, and vice versa, has to be partly rejected. The spatial distribution of vulnerability is not only dependent on the process intensities but also on the overall land use pattern and the individual constructive characteristics of the buildings exposed. Generally, we suggest the use of a normal data model for test sites exceeding a minimum of 30 elements at risk exposed. As such, the study enhanced our understanding of spatial vulnerability patterns on a local scale.     

Community-based disaster risk and vulnerability models of a coastal municipality in Bangladesh

Bangladesh is one of the most natural hazard-prone countries in the world with the greatest negative consequences being associated with cyclones, devastating floods, riverbank erosion, drought, earthquake, and arsenic contamination, etc. One way or other, these natural hazards engulfed every corner of Bangladesh. The main aim of this research paper is to carry out a multi-hazards risk and vulnerability assessment for the coastal Matlab municipality in Bangladesh and to recommend possible mitigation measures. To this aim, hazards are prioritized by integrating SMUG and FEMA models, and a participation process is implemented so as to involve community both in the risk assessment and in the identification of adaptation strategies. The Matlab municipality is highly vulnerable to several natural hazards such as cyclones, floods, and riverbank erosion. The SMUG is a qualitative assessment, while FEMA is a quantitative assessment of hazards. The FEMA model suggests a threshold of highest 100 points. All hazards that total more than 100 points may receive higher priority in emergency preparedness and mitigation measures. The FEMA model, because it judges each hazard individually in a numerical manner, may provide more satisfying results than the SMUG system. The spatial distributions of hazard, risk, social institutions, land use, and other resources indicate that the flood disaster is the top environmental problem of Matlab municipality. Hazard-specific probable mitigation measures are recommended with the discussion of local community. Finally, this study tries to provide insights into the way field research combining scientific assessments tools such as SMUG and FEMA could feed evidence-based decision-making processes for mitigation in vulnerable communities.     

山区道路泥石流减灾问题与对策

文章通过分析我国山区道路泥石流防治的特点与需求,认为山区道路潜在泥石流的判识与预测、泥石流对线路展布的制约、泥石流对道路工程设计的影响等是山区道路建设的关键技术问题。在山区建设中应研究潜在泥石流的判识方法、发展山区道路选线理论、认识道路工程与环境相互作用机制、创建与环境协调的道路工程反馈设计理论、构建山区道路泥石流减灾技术体系、开发道路环境灾害信息系统等工作。系统分析了道路勘察选线、个体工程设计、施工、运营阶段应注意的泥石流防治问题,根据不同阶段的灾害危害方式与特征,提出道路建设不同阶段的泥石流防治对策。     

An integrated approach for evaluating the effectiveness of landslide risk reduction in unplanned communities in the Caribbean

Despite the recognition of the need for mitigation approaches to landslide risk in developing countries, the delivery of ‘on-the-ground’ measures is rarely undertaken. With respect to other ‘natural’ hazards, it is widely reported that mitigation can pay. However, the lack of such an evidence base in relation to landslides in developing countries hinders advocacy amongst decision makers for expenditure on ex-ante measures. This research addresses these limitations directly by developing and applying an integrated risk assessment and cost–benefit analysis of physical landslide mitigation measures implemented in an unplanned community in the Eastern Caribbean. In order to quantify the level of landslide risk reduction achieved, landslide hazard and vulnerability were modelled (before and after the intervention), and project costs, direct and indirect benefits were monetised. It is shown that the probability of landslide occurrence has been substantially reduced by implementing surface-water drainage measures and that the benefits of the project outweigh the costs by a ratio of 2.7–1. This paper adds to the evidence base that ‘mitigation pays’ with respect to landslide risk in the most vulnerable communities—thus strengthening the argument for ex-ante measures. This integrated project evaluation methodology should be suitable for adoption as part of the community-based landslide mitigation project cycle, and it is hoped that this resource, and the results of this study, will stimulate further such programmes.     

Vulnerability assessment based on household views from the Dammar Char in Southeastern Bangladesh

Assessing vulnerability is vital for developing new strategies and improving the existing ones to fulfill contemporary demands toward achieving a disaster-resilient society. Dammar Char is situated in the southeastern (SE) coastal region of Bangladesh that has experienced frequent coastal hazards and disasters throughout the year. The present study has constructed a vulnerability index utilizing the quantitative and qualitative data based on household surveys to evaluate the vulnerability of the people and community of Dammar Char. Data were collected from 180 respondents during November–December 2018. The results demonstrate that, on average, the people living in the studied area have a high vulnerability (value of the vulnerability index 0.7015) to coastal hazards and disasters. The vulnerability level differs from individual to individual based on their gender, educational status, financial capacity, structural strength of houses, perception of the respective hazards and disasters, etc. Females have experienced more vulnerability than their adult male counterparts. The natural vulnerability was higher than socioeconomic and physical vulnerability due to the increase in unpredictable extreme climate-induced coastal events. To combat the adverse impacts of coastal hazards and disasters, the local Dammar Char inhabitants have adopted several adaptation measures. The adapted measures are homestead gardening, working in seasonal day labor, fish drying, rearing sheep, and ducks, constructing plinths for elevating the floor of the house, extensive banana cultivation, and storage of dry foods to reduce their vulnerability.

     

Regional vulnerability assessment for debris flows in China—a CWS approach

Based on former conceptual models of vulnerability, this paper aims to improve the quantitative model for regional vulnerability assessment by analyzing in-depth the relation between vulnerability, exposure, coping capacity, and resilience. Taking the mountain settlements in the upper reaches of Min River, China, as a case study, the method of Contributing Weight Superposition (CWS) is applied in establishing both a model and a system for the vulnerability assessment of elements at risk. The CWS approach consists of 13 index factors including population, economic and road densities, building and farmland coverage, hazard-affected areas, urbanization rate, and GDP per capita. Accordingly, a debris flow hazard vulnerability zoning map was obtained and the assessment results show that the distribution of high and comparatively high vulnerability zones, where economic activities are considerably high, has a close correlation to the topography of the catchment and population characteristics. The results thus may serve as a pertinent guidance for settlement relocation, population distribution readjustment, and management to prevent and reduce hazards in the upper reaches of Min River and beyond.     

A typological framework for categorizing infrastructure vulnerability

The concept of vulnerability is increasingly important in engineering and the socio-economic planning sciences, particularly given the enormous costs associated with addressing it. The ability to identify and mitigate vulnerabilities is extremely challenging because it is influenced by a complex and dynamic set of interacting factors that can compromise social, economic and infrastructure systems. Where the latter is concerned, the ability to assess infrastructure vulnerability involves the consideration of a range of physical, operational, geographical and socio-economic characteristics. In this paper, significant elements of infrastructure vulnerability are identified and discussed with a focus on their intrinsic spatial nature and their propensity to interact across space. Further, the developed typology of vulnerability outlined in this paper emphasizes the need to ensure that policy, planning and disaster mitigation efforts are strongly integrated at global, regional and local levels.     

中小流域山洪危险性区划

山洪危险性区域划分是一种行之有效的防洪减灾非工程措施,是防洪减灾体系中的重要组成部分.利用GIS技术和模糊数学方法建立山洪危险性评价模型;从山洪危险性定义出发,利用正交设计方法,考察降雨量和单位面积汇流时间等对山洪影响的敏感性,确定了合理的山洪危险性评价指标体系并结合层次分析法确定了评价指标权重.选择淮河上游息县流域进行了实证应用分析,对研究区域山洪危险性空间分布进行划分.研究结果表明:单位面积汇流时间短、地势起伏较大的地区是山洪危险性较大的区域,需要加强防治.      

Vulnerability assessments and their planning implications: a case study of the Hutt Valley, New Zealand

An understanding of vulnerability is not only crucial for the survival of the exposed communities to extreme events, but also for their adaptation to climate change. Vulnerability affects community participation in hazard mitigation, influences emergency response and governs adaptive capacity for the changing environmental and hazards characteristics. However, despite increased awareness, assessments and understanding of the processes that produce vulnerability, disaster risks prevail. This raises questions on the effectiveness of vulnerability assessments and their applications for hazard mitigation and adaptation. The literature includes a range of vulnerability assessment methods, wherein frequently the selection of any particular method is governed by the research objectives. On the other hand, hazard mitigation plans and policies even though mention vulnerability, their implementation pays less attention to the variations in its nature and underlying causes. This paper explores possible reasons for such gaps by exploring a case study of the Hutt Valley, New Zealand. It brings out the limitations of different vulnerability assessment methods in representing the local vulnerability and challenges they bring in planning for the vulnerability reduction. It argues that vulnerability assessment based on any particular method, such as deprivation index, principle component analysis, composite vulnerability index with or without weight, may not reveal the actual vulnerability of a place, and therefore, a comprehensive vulnerability assessment is needed.     

Mountain hazards and the resilience of social–ecological systems: lessons learned in India and Canada

Mountain regions are subject to a variety of hazardous processes. Earthquakes, landslides, snow avalanches, floods, debris flows, epidemics and fires, among other processes, have caused injury, death, damage and destruction. They also face challenges from increased populations, and expansion and intensification of␣activities, land uses and infrastructure. The combination of a dynamic bio- geophysical environment and intensified human use has increased the vulnerability of mountain social–ecological systems to risk from hazards. The ability of social–ecological systems to build resilience in the context of hazards is an important factor in their long-term sustainability. The role of resilience building in understanding the impact of hazards in mountain areas is examined and illustrated, in part, through examples from Canada and India. Resilient social–ecological systems have the ability to learn and adjust, use all forms of knowledge, to self-organize and to develop positive institutional linkages with other social–ecological systems in the face of hazards. The analysis suggests that traditional social–ecological systems built resilience through avoidance, which was effective for localized hazards. The more recent development and implementation of cross-scale institutional linkages is shown to be a particularly effective means of resilience building in mountain social–ecological systems in the face of all hazards.