Multi-hazard Risk Assessment Research Articles

Supporting Resilience to Natural Hazards in East Asia and the Pacific

Natural hazards and its adverse implications on economic growth limit the progress of sectoral development at national and sub-national level. This is true in the context of East Asia and the Pacific which is highly exposed to such natural hazards. Therefore, the region is seeking co-operation in Disaster Risk Management (DRM) assessment and disaster risk financing and insurance. Considering the above, this study provides an overview of DRM practice in the region. The findings of the study suggest that the region is facing obstacles such as lack of knowledge and technical capacity limits the ability of many countries in East Asia and the Pacific to assess risks accurately and access to national multi-hazard risk assessment. Hence, there is a need for Investing in-country technical capacity, integrate risk information into the decision-making process, bridge the gap between stakeholders to build collective resilience and risk identification activities. In addition, sharing the risk information with key stakeholders will help to protect their assets. In the end, benchmarking activities in raising awareness from the governments will help to increase transparency and accountability.

Application of geospatial technologies for multi-hazard mapping and characterization of associated risk at local scale

ABSTRACTIn this study multi-hazard risk assessment is carried out in Arithang ward, one of the major wards within Gangtok Municipal Corporation, with the objectives of (a) landslide and earthquake hazard mapping of Gangtok city with analytical hierarchy process (b) vulnerability mapping in Arithang ward and (c) semiquantitative and semiqualitative risk analysis. Landslide hazard zonation (LHZ) depicts that very high and high hazard zone occupies 6% and 17% of the Gangtok city whereas 60% and 18% of area falls under medium and low hazard category respectively. With respect to seismic hazard susceptibility 13% and 22% of area falls under very high and high category respectively. Semiquantitative risk analysis reveals that majority of the residential buildings are concentrated in low earthquake and landslide hazard zone followed by 39% and 35% within medium class. Only 0.6% and 7% of residential buildings are found in high earthquake and landslide hazard zones. Bamboo and wood made buildings are found to cluster within very high class of landslide hazard. About 61% of multistoried buildings are placed within low zone of LHZ. Risk analysis reveals that buildings at the eastern and western part of Arithang ward come under high risk with respect to earthquake and landslide.

Evaluating the impacts of volcanic eruptions using RiskScape

RiskScape is a free multi-hazard risk assessment software programme jointly developed by GNS Science and the National Institute of Water and Atmospheric Research (NIWA) in New Zealand. RiskScape has a modular structure, with hazard layers, assets, and loss functions prepared separately. While RiskScape was originally developed for New Zealand, given suitable hazard and exposed asset information, RiskScape can be run anywhere in the world. Volcanic hazards are among the many hazards considered by RiskScape. We first present RiskScape’s framework for all hazards, and then describe in more detail the five volcanic hazards – tephra deposition, pyroclastic density currents, lava flows, lahars, and edifice construction/excavation. We describe how loss functions were selected and developed. We use a scenario example to illustrate not only how RiskScape’s volcanic module works but also how RiskScape can be used to compare across natural hazards.

Multi-hazard risk assessment of coastal vulnerability from tropical cyclones – A GIS based approach for the Odisha coast

The coastal region bordering the East coast of India is a thickly populated belt exposed to high risk and vulnerability from natural hazards such as tropical cyclones. Tropical cyclone frequencies that develop over the Bay of Bengal (average of 5–6 per year) region are much higher as compared to the Arabian Sea thereby posing a high risk factor associated with storm surge, inland inundation, wind gust, intense rainfall, etc. The Odisha State in the East coast of India experiences the highest number of cyclone strikes as compared to West Bengal, Andhra Pradesh, and Tamil Nadu. To express the destructive potential resulting from tropical cyclones the Power Dissipation Index (PDI) is a widely used metric globally. A recent study indicates that PDI for cyclones in the present decade have increased about six times as compared to the past. Hence there is a need to precisely ascertain the coastal vulnerability and risk factors associated with high intense cyclones expected in a changing climate. As such there are no comprehensive studies attempted so far on the determination of Coastal Vulnerability Index (CVI) for Odisha coast that is highly prone to cyclone strikes. With this motivation, the present study makes an attempt to investigate the physical, environmental, social, and economic impacts on coastal vulnerability associated with tropical cyclones for the Odisha coast. The study also investigates the futuristic projection of coastal vulnerability over this region expected in a changing climate scenario. Eight fair weather parameters along with storm surge height and onshore inundation were used to estimate the Physical Vulnerability Index (PVI). Thereafter, the PVI along with social, economic, and environmental vulnerability was used to determine the overall CVI using the GIS based approach. The authors believe that the comprehensive nature of this study is expected to benefit coastal zone management authorities.

Integration of Probabilistic and Multi-Hazard Risk Assessment Within Urban Development Planning and Emergency Preparedness and Response: Application to Manizales, Colombia

The details of a multi-hazard and probabilistic risk assessment, developed for urban planning and emergency response activities in Manizales, Colombia, are presented in this article. This risk assessment effort was developed under the framework of an integral disaster risk management project whose goal was to connect risk reduction activities by using open access and state-of-the-art risk models. A probabilistic approach was used for the analysis of seismic, landslide, and volcanic hazards to obtain stochastic event sets suitable for probabilistic loss estimation and to generate risk results in different metrics after aggregating in a rigorous way the losses associated to the different hazards. Detailed and high resolution exposure databases were used for the building stock and infrastructure of the city together with a set of vulnerability functions for each of the perils considered. The urban and territorial ordering plan of the city was updated for socioeconomic development and land use using the hazard and risk inputs and determinants, which cover not only the current urban area but also those adjacent areas where the expansion of Manizales is expected to occur. The emergency response capabilities of the city were improved by taking into account risk scenarios and after updating an automatic and real-time post-earthquake damage assessment.

Probabilistic risk assessment framework for structural systems under multiple hazards using Bayesian statistics

Conventional probabilistic risk assessment (PRA) methodologies (USNRC, 1983; IAEA, 1992; EPRI, 1994; Ellingwood, 2001) conduct risk assessment for different external hazards by considering each hazard separately and independent of each other. The risk metric for a specific hazard is evaluated by a convolution of the fragility and the hazard curves. The fragility curve for basic event is obtained by using empirical, experimental, and/or numerical simulation data for a particular hazard. Treating each hazard as an independently can be inappropriate in some cases as certain hazards are statistically correlated or dependent. Examples of such correlated events include but are not limited to flooding induced fire, seismically induced internal or external flooding, or even seismically induced fire. In the current practice, system level risk and consequence sequences are typically calculated using logic trees to express the causative relationship between events. In this paper, we present the results from a study on multi-hazard risk assessment that is conducted using a Bayesian network (BN) with Bayesian inference. The framework can consider statistical dependencies among risks from multiple hazards, allows updating by considering the newly available data/information at any level, and provide a novel way to explore alternative failure scenarios that may exist due to vulnerabilities.

Risk assessment framework for exposure of cargo and ports to natural hazards and climate extremes

ABSTRACTThere is an increase in risks and catastrophic losses in maritime transport including ports and cargo. Significant losses have been associated with large scale natural hazards, such as earthquakes, tsunami, cyclones, and other extreme weather events. This paper identifies the main gaps in understanding maritime risks in transportation research. The gaps are attributed to insufficient empirical work available from the maritime transport and logistics research community to guide multi-risk and natural hazards impact assessment on seaport and cargo. In addition, disaster studies communities have barely made adequate efforts to understand and assess port and cargo risks arising from multi-hazards and disaster events. This paper examines existing conceptual frameworks concerning exposure and risk assessments of natural catastrophe’s impacts. Furthermore, the paper identifies trends and gaps in risk assessment frameworks in the field of disaster studies that can be beneficial for maritime risk research. The authors propose a new risk assessment framework that can guide future research and multi-hazard risk assessment processes at different scales of maritime risks.

Multihazard Risk Assessment of Electric Power Systems

AbstractElectric power systems are susceptible to damage due to natural hazards such as hurricanes and earthquakes. Considerable effort has been made to develop methodologies for assessing the reliability of electric power systems under a single hazard such as hurricanes or earthquakes. However, there are parts of the world, such as the coastal areas of South Carolina, which are affected by both hazards. In such regions, more comprehensive risk assessment can be achieved when the focus is shifted from single-hazard to multihazard analysis. There is, therefore, a need to develop methods for quantifying the risk posed by the combined effect of multiple hazards on structures and infrastructure systems in these regions. This paper presents a framework for multihazard risk assessment of electric power systems subjected to seismic and hurricane wind hazards. The framework includes hazard and structural component vulnerability models, system reliability analysis, and multihazard risk assessment. A notional elect...

Multi-hazard risk assessment of two Hong Kong districts

The assessment of multi-hazard risks in urban areas poses particular difficulties due to the different temporal and spatial scales of hazardous events, and the potential interactions between hazards and socio-economic fragilities. Yet this exercise is important, as identifying the spatial distribution and concentration of risks in urban areas helps determine where and how preventive and corrective actions can reduce levels of vulnerability and exposure of urban populations. This article presents the results of a GIS-based assessment of present day risk to socio-natural hazards in two socio-economically distinct districts of Hong Kong (PRC) by utilizing indicators to describe the hazards and vulnerabilities. Hong Kong is a densely populated coastal metropolis exposed to multiple intense and potentially overlapping hydro-meteorological hazards, including heat waves, typhoons, and landslides. Mapping hazards and vulnerabilities in this urban area helps to visualize the spatial distribution and concentrations of risk located throughout the city, and thereby facilitate the tailoring of measures that can reduce risk at the very local scale. This approach has the potential of providing city planners and policy makers with visual guidance in prioritizing risk management and adaptation actions with respect to current and future risks existing in specific parts of the city, taking into account more than one hazard at the time. We found that the two districts considered have comparable and distributed levels of risk being both exposed to multiple hazards and notwithstanding the socio-economic groups. However, elements of criticality are potentially more widespread in the less wealthy parts of the city.

Integrating expert opinion with modelling for quantitative multi-hazard risk assessment in the Eastern Italian Alps

Extreme rainfall events are the main triggering causes for hydro-meteorological hazards in mountainous areas, where development is often constrained by the limited space suitable for construction. In these areas, hazard and risk assessments are fundamental for risk mitigation, especially for preventive planning, risk communication and emergency preparedness. Multi-hazard risk assessment in mountainous areas at local and regional scales remain a major challenge because of lack of data related to past events and causal factors, and the interactions between different types of hazards. The lack of data leads to a high level of uncertainty in the application of quantitative methods for hazard and risk assessment. Therefore, a systematic approach is required to combine these quantitative methods with expert-based assumptions and decisions. In this study, a quantitative multi-hazard risk assessment was carried out in the Fella River valley, prone to debris flows and flood in the north-eastern Italian Alps. The main steps include data collection and development of inventory maps, definition of hazard scenarios, hazard assessment in terms of temporal and spatial probability calculation and intensity modelling, elements-at-risk mapping, estimation of asset values and the number of people, physical vulnerability assessment, the generation of risk curves and annual risk calculation. To compare the risk for each type of hazard, risk curves were generated for debris flows, river floods and flash floods. Uncertainties were expressed as minimum, average and maximum values of temporal and spatial probability, replacement costs of assets, population numbers, and physical vulnerability. These result in minimum, average and maximum risk curves. To validate this approach, a back analysis was conducted using the extreme hydro-meteorological event that occurred in August 2003 in the Fella River valley. The results show a good performance when compared to the historical damage reports.

A quantitative model for estimating risk from multiple interacting natural hazards: an application to northeast Zhejiang, China

Multi-hazard risk assessment is a major concern in risk analysis, but most approaches do not consider all hazard interactions when calculating possible losses. We address this problem by developing an improved quantitative model—Model for multi-hazard Risk assessment with a consideration of Hazard Interaction (MmhRisk-HI). This model calculates the possible loss caused by multiple hazards, with an explicit consideration of interaction between those hazards. There are two main components to the model. In the first, based on the hazard-forming environment, relationships among hazards are classified into four types for calculation of the exceedance probability of multiple hazards occurrence. In the second, a Bayesian network is used to calculate possible loss caused by multiple hazards with different exceedance probabilities. A multi-hazard risk map can then be drawn addressing the probability of multi-hazard occurrence and corresponding loss. This model was applied in northeast Zhejiang, China and validated by comparison against an observed multi-hazard sequence. The validation results show that the model can more effectively represent the real world, and that the modelled outputs, possible loss caused by multiple hazards, are reliable. The outputs can additionally help to identify areas at greatest risk, and allows a determination of the factors that contribute to that risk, and hence the model can provide useful further information for planners and decision-makers concerned with risk mitigation.

Hazard interaction analysis for multi-hazard risk assessment: a systematic classification based on hazard-forming environment

Abstract. This paper develops a systematic hazard interaction classification based on the geophysical environment that natural hazards arise from – the hazard-forming environment. According to their contribution to natural hazards, geophysical environmental factors in the hazard-forming environment were categorized into two types. The first are relatively stable factors which construct the precondition for the occurrence of natural hazards, whilst the second are trigger factors, which determine the frequency and magnitude of hazards. Different combinations of geophysical environmental factors induce different hazards. Based on these geophysical environmental factors for some major hazards, the stable factors are used to identify which kinds of natural hazards influence a given area, and trigger factors are used to classify the relationships between these hazards into four types: independent, mutex, parallel and series relationships. This classification helps to ensure all possible hazard interactions among different hazards are considered in multi-hazard risk assessment. This can effectively fill the gap in current multi-hazard risk assessment methods which to date only consider domino effects. In addition, based on this classification, the probability and magnitude of multiple interacting natural hazards occurring together can be calculated. Hence, the developed hazard interaction classification provides a useful tool to facilitate improved multi-hazard risk assessment.

The danger of mapping risk from multiple natural hazards

In recent decades, society has been greatly affected by natural disasters (e.g. floods, droughts, earthquakes), and losses and effects caused by these disasters have been increasing. Conventionally, risk assessment focuses on individual hazards, but the importance of addressing multiple hazards is now recognised. Two approaches exist to assess risk from multiple hazards: the risk index (addressing hazards, and the exposure and vulnerability of people or property at risk) and the mathematical statistics method (which integrates observations of past losses attributed to each hazard type). These approaches have not previously been compared. Our application of both to China clearly illustrates their inconsistency. For example, from 31 Chinese provinces assessed for multi-hazard risk, Gansu and Sichuan provinces are at low risk of life loss with the risk index approach, but high risk using the mathematical statistics approach. Similarly, Tibet is identified as being at almost the highest risk of economic loss using the risk index, but lowest risk under the mathematical statistics approach. Such inconsistency should be recognised if risk is to be managed effectively, whilst the practice of multi-hazard risk assessment needs to incorporate the relative advantages of both approaches.

A Multi-hazard Risk Assessment Methodology, Stress Test Framework and Decision Support Tool for Transport Infrastructure Networks

Natural hazards can cause serious disruption to societies and their transport infrastructure networks. The impact of extreme hazard events is largely dependent on the resilience of societies and their networks. The INFRARISK project is developing a reliable stress test framework for critical European transport infrastructure to analyse the response of networks to extreme hazard events. The project considers the spatio-temporal processes associated with multi-hazard and cascading extreme events (e.g. earthquakes, floods, landslides) and their impacts on road and rail transport infrastructure networks. As part of the project, an operational framework is being developed using an online INFRARISK Decision Support Tool (IDST) to advance decision making approaches, leading to better protection of existing transport infrastructure. The framework will enable the next generation of European infrastructure managers to analyse the risk to critical road and rail infrastructure networks due to extreme natural hazard events. To demonstrate the overarching risk assessment methodology developed in the project, the methodology is demonstrated for two case studies, which comprise portions of the European TEN-T network; a road network in the region of Bologna, Italy and a rail network extending from Rijeka to Zagreb in Croatia. This paper provides an overview of the INFRARISK multi-hazard risk assessment methodology and a brief introduction to the case studies, as the project is currently ongoing. INFRARISK is funded by the European Commission's FP7 programme, Grant Agreement No. 603960. Further information can be found at www.infrarisk-fp7.eu.

A physically-based multi-hazard risk assessment platform for regional rainfall-induced slope failures and debris flows

Rainfall-induced slope failures and debris flows are two major hazards in mountainous areas. A physically-based multi-hazard risk assessment platform for regional rainfall-induced slope failures and debris flows has been developed in this study. The platform enables prompt assessment of risks posed by regional rainfall-induced slope failures and debris flows across multiple catchments, which is required in landslide risk management in a large area. It considers the contribution of slope failures to debris flows and the scenario of a location impacted by multiple slope failures or debris flows or both. The contribution of slope failures to debris flows is considered by adding the increased amount of channel deposit from slope failures to the source material of debris flows. The platform is applied to a highway near the epicentre of the 2008 Wenchuan earthquake. The platform predicts the impact areas and runout distances of regional debris flows reasonably well. The risk assessment results indicate that both slope failures and debris flows pose a great danger to travellers along the road shortly after the earthquake due to the presence of a large amount of loose landslide deposits on steep terrains. The materials from the slope failures triggered during a storm substantially increase the channel deposit volume, leading to significantly increased debris flow volume and risk. A multi-hazard risk assessment approach is necessary to consider the scenario of a location impacted by multiple slope failures or debris flows or both, since assessing risks of slope failures and debris flows separately may underestimate the risk.

Urban seismic risk index for Medellín, Colombia, based on probabilistic loss and casualties estimations

Medellin is the second largest city of Colombia with more than 2 million inhabitants according to the latest census and with more than 240,000 public and private buildings. It is located on an intermediate seismic hazard area according to the seismic zonation of Colombia although no destructive earthquakes have occurred having as a consequence low seismic risk awareness among its inhabitants. Using the results of a fully probabilistic risk assessment of the city with a building by building resolution level and considering the dynamic soil response, average annual losses by sectors as well as casualties and other direct effects are obtained and aggregated at county level. Using the holistic evaluation module of the multi-hazard risk assessment CAPRA platform, EvHo, a comprehensive assessment that considered the social fragility and lack or resilience at county level is performed making use of a set of indicators with the objective of capturing the aggravating conditions of the initial physical impact. The urban seismic risk index, USRi, is obtained at county level which is useful to communicate risk to decision-makers and stakeholders besides making easy identifying potential zones that can be problematic in terms of several dimensions of the vulnerability. This case study is an example of how a multidisciplinary research on disaster risk reduction helps to show how risk analysis can be of high relevance for decision-making processes in disaster risk management.

Multi hazards risk assessment, a new methodology

Background: Multi-hazards pose a serious threat to human life. It can cause considerable damages. The evaluation of the expected losses due to multi-hazards requires a risk assessment. Multi-hazards risk assessment allow the identification of the most endangered areas and suggest where further detailed studies have to be carried out. Aim: This study aims to give a new methodology for Multi-hazard risk assessment that makes easier the comparability analysis of vulnerability for different hazards and accounts for possible triggering (domino) effects. Materials and Methods: Methods used in this paper are based on theoretical approach and documentation. Two types of hazards will be assessed, namely earthquake and fire following earthquake. Statistical Analysis: Semi-quantitative and quantitative approach would assess risk rates at both regional and local levels. Result: In this study, representation of a new methodology for multi-hazards risk assessment includes determination of a model with parameters, consideration of the indicator-based pattern of vulnerability assessment that selected of all the relevant indicators and presented new classification of indicators based on comparison to different hazards and possible triggering (domino) effects. This means a potential multi-hazard indicator could be higher than the simple aggregation of single risk indicators calculation. Conclusion: The focus is on establishing a general overview of the emerging issues, and indicating how hazard relations can be considered in multi-hazard studies. The hazard relation is identified and studied by means of a new method and the overlay of hazard areas to determine overlaps in final multi-hazards map.

A Multi-hazard Risk Assessment of Buildings in Padang City

The main purpose of an earthquake risk assessment is to assess the potential loss of buildings in earthquake prone regions and to provide enough information to employ suitable mitigation strategies. The Mw 9.1 great Sumatra earthquake in 2004 and the Mw 9.0 Japan earthquake in 2011 have highlighted the importance of a multi-hazard risk assessment framework that includes the effects of both earthquake and its associated hazards such as tsunami. The multi-hazard risk assessment of buildings requires several stages including earthquake and tsunami hazard analyses, the vulnerability analysis of buildings, building inventory as well as the risk estimation of buildings in the investigated area, which are discussed in this paper. The method on how to incorporate these stages into a multi-hazard risk assessment framework is also presented. The developed risk assessment framework is then used for the city of Padang that has a considerably high earthquake and tsunami hazard with great exposure to population and infrastructures. The estimated risk obtained in this study is expressed in terms of Pure Risk Premium (PRP) for different building categories commonly found in Padang including unreinforced brick masonry (UBM), confined brick masonry (CBM), reinforced concrete frame with masonry infill (RCI) and steel structures. The earthquake PRP(s) obtained in this study are comparable with the latest insurance rates released by MAIPARK. MAIPARK is an insurance company specialized in earthquake reinsurance, which also provides earthquake statistics and sets a benchmark for earthquake insurance pricing in Indonesia. Tsunami PRP(s) for different building categories in the area are also presented in this paper; however, no comparison can be made due to the unavailability of tsunami insurance premium data for Indonesia. Based on the results, it can be concluded that building risk associated with tsunami in Padang is considerably lower than that of earthquake, due to infrequent occurrence of tsunamis in the area. The earthquake and tsunami risk of buildings in Padang is predicted to be £54.5 million and £30.8 million per annum, respectively.

Quantitative multi-hazard risk assessment with vulnerability surface and hazard joint return period

Risk assessment plays an important role in disaster risk management. Existing multi-hazard risk assessment models are often qualitative or semi-quantitative in nature and used for comparative study of regional risk levels. They cannot estimate directly probability of disaster losses from the joint impact of several hazards. In this paper, a quantitative approach of multi-hazard risk assessment based on vulnerability surface and joint return period of hazards is put forward to assess the risk of crop losses in the Yangtze River Delta region of China. The impact of strong wind and flood, the two most prominent agricultural hazards in the area, is analyzed. The multi-hazard risk assessment process consists of three steps. First, a vulnerability surface, which denotes the functional relationship between the intensity of the hazards and disaster losses, was built using the crop losses data for losses caused by strong wind and flood in the recent 30 years. Second, the joint probability distribution of strong wind and flood was established using the copula functions. Finally, risk curves that show the probability of crop losses in this multi-hazard context at four case study sites were calculated according to the joint return period of hazards and the vulnerability surface. The risk assessment result of crop losses provides a useful reference for governments and insurance companies to formulate agricultural development plans and analyze the market of agricultural insurance. The multi-hazard risk assessment method developed in this paper can also be used to quantitatively assess multi-hazard risk in other regions.

Special Issue on Performance of Timber and Hybrid Structures

Special Issue on Performance of Timber and Hybrid Structures