Towards an empirical vulnerability function for use in debris flow risk assessment

Abstract. In quantitative risk assessment, risk is expressed as a function of the hazard, the elements at risk and the vulnerability. From a natural sciences perspective, vulnerability is defined as the expected degree of loss for an element at risk as a consequence of a certain event. The resulting value is dependent on the impacting process intensity and the susceptibility of the elements at risk, and ranges from 0 (no damage) to 1 (complete destruction). With respect to debris flows, the concept of vulnerability – though widely acknowledged – did not result in any sound quantitative relationship between process intensities and vulnerability values so far, even if considerable loss occurred during recent years. To close this gap and establish this relationship, data from a well-documented debris flow event in the Austrian Alps was used to derive a quantitative vulnerability function applicable to buildings located on the fan of the torrent. The results suggest a second order polynomial function to fit best to the observed damage pattern. Vulnerability is highly dependent on the construction material used for exposed elements at risk. The buildings studied within the test site were constructed by using brick masonry and concrete, a typical design in post-1950s building craft in alpine countries. Consequently, the presented intensity-vulnerability relationship is applicable to this construction type within European mountains. However, a wider application of the presented method to additional test sites would allow for further improvement of the results and would support an enhanced standardisation of the vulnerability function.

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Integrating rockfall risk assessment and countermeasure design by 3D modelling techniques

Natural Hazards and Earth System Science ◽

10.5194/nhess-9-1059-2009 ◽

2009 ◽

Vol 9 (4) ◽

pp. 1059-1073 ◽

Cited By ~ 100

Author(s):

F. Agliardi ◽

G. B. Crosta ◽

P. Frattini

Keyword(s):

Risk Assessment ◽

At Risk ◽

Back Analysis ◽

Quantitative Risk Assessment ◽

Assessment Procedure ◽

Area At Risk ◽

Technical Performance ◽

Mitigation Action ◽

Observed Damage ◽

The Cost

Abstract. Rockfall risk analysis for mitigation action design requires evaluating the probability of rockfall events, the spatial probability and intensity of impacts on structures, their vulnerability, and the related expected costs for different scenarios. These tasks were integrated in a quantitative risk assessment procedure supported by 3D rockfall numerical modelling performed by the original code HY-STONE. The case study of Fiumelatte (Varenna, Italy), where a large rockfall in November 2004 resulted in 2 casualties, destruction of several buildings and damage to transportation corridors, is discussed. The numerical model was calibrated by a back analysis of the 2004 event, and then run for the whole area at risk by considering scenarios without protection (S0), with a provisional embankment (S1), and with a series of long-term protection embankments (S2). Computed impact energy and observed damage for each building impacted in 2004 were combined to establish an empirical vulnerability function, according to which the expected degree of loss for each element at risk was computed. Finally, costs and benefits associated to different protection scenarios were estimated, in order to assess both the technical performance and the cost efficiency of different mitigation options.

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Risk Assessment of Debris Flows along a Road Considering Redistribution of Elements at Risk

Geo-Risk 2017 ◽

10.1061/9780784480717.019 ◽

2017 ◽

Author(s):

H. X. Chen ◽

L. M. Zhang ◽

Shi-Jin Feng

Keyword(s):

Risk Assessment ◽

At Risk ◽

Debris Flows ◽

Elements At Risk

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The Whittier Narrows, California Earthquake of October 1, 1987—Buildings at Risk

Earthquake Spectra ◽

10.1193/1.1585463 ◽

1988 ◽

Vol 4 (1) ◽

pp. 35-42 ◽

Cited By ~ 3

Author(s):

B. G. Jones ◽

C. N. Nicolaides

Keyword(s):

Risk Assessment ◽

At Risk ◽

Incidence Rates ◽

Replacement Cost ◽

Population Number ◽

Floor Area ◽

Physical Context ◽

Elements At Risk

Current methods of risk assessment require determining the incidence of damage to the elements at risk in order to establish vulnerability. Recent disasters can provide extremely useful information for calibrating various parameters of damage rates. It is necessary to produce estimates of the elements at risk and apply the best information available concerning damage. This requires considering the total physical context in which the disaster occurred. We estimate population, number of buildings, building floor area, and building replacement cost for the Modified Mercalli Intensity VI, VII and VIII areas for the Whittier Narrows Earthquake and calculate incidence rates.

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Estimation of the regional stock of residential buildings as a basis for a comparative risk assessment in Germany

Natural Hazards and Earth System Science ◽

10.5194/nhess-6-541-2006 ◽

2006 ◽

Vol 6 (4) ◽

pp. 541-552 ◽

Cited By ~ 46

Author(s):

L. Kleist ◽

A. H. Thieken ◽

P. Köhler ◽

M. Müller ◽

I. Seifert ◽

...

Keyword(s):

Risk Assessment ◽

At Risk ◽

Residential Buildings ◽

Quantitative Risk Assessment ◽

Risk Map ◽

Comparative Risk Assessment ◽

Financial Appraisal ◽

Different Types ◽

Comparative Risk ◽

Year 2000

Abstract. One important prerequisite for a comparable quantitative risk assessment for different types of hazards (e.g., earthquakes, windstorms and floods) is the use of a common database about and financial appraisal of the assets at risk. For damage assessments it is necessary to represent the values at risk on a regional disaggregated scale and to intersect them with hazard scenarios. This paper presents a methodology and results of a financial appraisal of residential buildings for all communities in Germany. The calculated values are defined as replacement values for the reference year 2000. The resulting average replacement costs for residential buildings per inhabitant amount to EUR 46 600, with considerable differences between communities. The inventory can be used for the calculations of direct losses from various natural disasters within the project "Risk Map Germany''.

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AN INDICATOR-BASED APPROACH FOR MICRO-SCALE PHYSICAL FLOOD VULNERABILITY MAPPING

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprs-archives-xlii-4-w16-331-2019 ◽

2019 ◽

Vol XLII-4/W16 ◽

pp. 331-337

Author(s):

I. U. Kaoje ◽

M. Z. Abdul Rahman ◽

T. H. Tam ◽

M. R. Mohd Salleh

Keyword(s):

Risk Assessment ◽

At Risk ◽

Vulnerability Assessment ◽

Flood Risk ◽

Vulnerability Mapping ◽

Rapid Urbanization ◽

Flood Vulnerability ◽

Protection Measures ◽

Micro Scale ◽

Elements At Risk

Abstract. Map representation of vulnerability is a crucial step in evaluating flood impact and all vulnerability indicators that are the final product of risk assessment. So far, in flood risk assessment, this is probably the weakest link. Flood risk mapping suffers from inequality in the level of development in presenting the different components: where exposure and hazard modelling and mapping is well developed and advanced, while vulnerability analysis and mapping are underdeveloped. Therefore, the objective of this paper is to discuss a newly developed GIS-based approach on micro-scale flood vulnerability mapping of physical elements at risk using an indicator-based method. Micro-scale flood vulnerability is used to eliminate flood vulnerability in an area with a high probability of occurrences. The approach is suitable for cost-benefit analysis of structures protection measures. At micro-scale flood vulnerability mapping, it is more suitable to adopt indicator-based vulnerability assessment methods. Because it provides an opportunity for incorporating all the factors and characteristics of elements at risk that contribute to generating their flood vulnerability. Likewise, a considerable amount of studies argue that vulnerability assessment and its representation on maps should focus on the identification of variables that influence the vulnerability of an element at risk. Flood vulnerability mapping at micro-scale provides critical information for the decision-makers on why specific infrastructures are susceptible more than the others. Moreover, assessing and managing flood risk is crucial in order to reduce the loss and adapt to the combined effects of rapid urbanization and climate changes.

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The assessment of quantitative risk to road users from debris flow

Geoenvironmental Disasters ◽

10.1186/s40677-019-0140-x ◽

2020 ◽

Vol 7 (1) ◽

Cited By ~ 2

Author(s):

M. G. Winter ◽

J. C. F. Wong

Keyword(s):

Risk Assessment ◽

Debris Flow ◽

High Frequency ◽

Low Frequency ◽

Quantitative Risk Assessment ◽

Road Users ◽

High Magnitude ◽

The Impact ◽

Level Of Risk ◽

Low Magnitude

Abstract Background A methodology for the quantitative risk assessment (QRA) of the impact of debris flow in a road environment has been developed and applied to two sites that are typically subject to high frequency-low magnitude and low frequency-high magnitude events. The methodology considers the probability of an event of a typical size, and the conditional probabilities of a vehicle being affected, given an event, and of damage (fatality) occurring given that the vehicle is affected. Scenarios covering a vehicle being hit by a debris flow and of a vehicle hitting a debris flow are considered. The computed Personal Individual Risk (PIR) is used to calculate worst case fatality probabilities for commuters and logistics truck drivers. The overall risk to society is expressed both by the annual probability of fatality amongst all road users, the Potential Loss of Life (PLL), and using the F-N diagram and is used to demonstrate the effect of a programme of management and mitigation works on the societal risk at one of the sites. The authors believe that this is the first full, formal quantitative risk assessment for debris flow risk to road users. Results The PIR for a single trip through the sites ranges between 1.147E-10 for the low frequency-high magnitude site and 1.583E-09 for the high frequency-low magnitude site. These figures increase to 1.248E-07 and 1.922E-06, respectively, when more frequent travellers are considered. The PLL for the two sites ranges between 2.616E-04 for the low frequency-high magnitude site and 4.083E-03 for the high frequency-low magnitude site. The F-N diagrams illustrate the Broadly Acceptable level of risk at the low frequency-high magnitude site and the partially Unacceptable level of risk at the high frequency-low magnitude site. The risk at the high frequency-low magnitude site is reduced to ALARP levels when management and mitigation measures extant as of October 2014 are considered. Conclusions The QRA proves an effective technique for understanding, comparing and articulating the differences in levels of risk and the temporal changes in risk at a given site as a result of landslide risk reduction activities.

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Back-analysis of rockfalls for the definition of an empirical vulnerability function for buildings

10.5194/egusphere-egu2020-11244 ◽

2020 ◽

Author(s):

Sandra Melzner ◽

Paolo Frattini ◽

Federico Agliardi ◽

Giovanni Battista Crosta

Keyword(s):

At Risk ◽

Back Analysis ◽

Quantitative Risk Assessment ◽

High Quality ◽

Damage Data ◽

Element At Risk ◽

Definition Of ◽

Observed Damage ◽

Probability Density Distributions ◽

The Impact

The vulnerability of buildings to the impact of rockfalls is a key component of Quantitative Risk Assessment for rockfall phenomena. Only a few attempts to quantitatively assess vulnerability have been presented in the literature due to the lack of high-quality rockfall and damage data. For processes such as debris flows, snow avalanches or earthquakes, well-established methods for the estimation of physical vulnerability are already available.The present work aims to develop an empirical rockfall vulnerability function by coupling rockfall back-analysis modelling of several damaging events occurred in different lithological and geomorphological settings. A sound database of damage to specific categories of structures impacted by rockfalls is build up by archive research of historical events and high-quality field observations of recent events. Damages are classified according to four damage types: superficial (degree of loss: 0.1-0.2) to structural (degree of loss: 1.0). The back-analysis of rockfalls and the interaction with element at risk is performed with the 3D numerical model Hy- STONE. The code uses a hybrid modelling approach and random sampling of input parameters from different probability density distributions (uniform, normal, exponential) to account for the complexity of the rockfall process and influencing factors. The elements at risk are integrated as lines to the model, impact points being able to be displayed and extracted as point vector data. This enables a precise analysis of simulated energies and observed damage for each building impacted in the past to define an empirical vulnerability function. The empirical vulnerability function is established by fitting damage-energy data through a sigmoidal function. This empirical vulnerability function for buildings is fundamental to compute the expected degree of loss for each element of risk, especially in areas where no detailed rockfall or damage data is available.

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Dynamic process and failure mechanism of rammed building structure subject to debris flow

10.5194/egusphere-egu21-13776 ◽

2021 ◽

Author(s):

Qiang Zou ◽

Cong Li ◽

Bin Zhou ◽

Zhenru Hu ◽

Hu Jiang

Keyword(s):

At Risk ◽

Dynamic Response ◽

Debris Flow ◽

Failure Mechanism ◽

Rammed Earth ◽

Building Structure ◽

Response Characteristics ◽

The Impact ◽

Debris Flow Hazard ◽

Elements At Risk

The failure mechanism of building structure is important for quantitatively assessing vulnerability of elements at risk, which is a critical step in risk assessment of debris flow. Scholars have recently made great processes in the researches on debris flow hazard effects and vulnerability of elements at risk. Statistical analysis methods have widely used to analyze field survey data and build vulnerability functions. Based on numerical simulation and model experiment, structural dynamic response process was analyzed to evaluate structure vulnerability. However, due to the lack of quantitative relationship between the debris flow hazard-forming mechanism and the dynamic response of building structure, it is essential to analyze the dynamic response characteristics and process of building structure subject to debris flow, which would play an important guiding role in disaster prevention and disaster mitigation.Through hazard field investigation, the failure modes of rammed earth building caused by debris flow were summarized as burying, scouring and impact. Figure 1 shows the debris flow hazard in Jiende Gully, Liangshan. In addition, by using the finite element analysis method, the structure model of rammed earth building was established to simulate to the impact process of debris flow on the structure. During the dynamic failure process of rammed earth building shown in Figure 2, the failure types of building wall impacted by the debris flow mainly presented at crushed failure of the impact point, tensile failure of the inside wall and shear failure of the corner. Then debris flow destroyed the gable wall, rushed into the room, and broke the doorway, which resulted in damage of the longitudinal wall. Moreover, the response characteristics and failure mechanism of rammed earth buildings under the impact of debris flow further show that the integrity of rammed earth building is poor and the development of cracks cuts off the propagation path of stress, which effectively protects other walls. The transform-shape locations of the rammed earth building including were initially destroyed at the points of the wall foundation, corners of wall and the points impacted by big rocks of debris flow. Therefore, the reinforced measures on the locations where stress suddenly changes, such as wall foundations and wall corners should be paid more attention to protect rammed structure of buildings.<img src="https://contentmanager.copernicus.org/fileStorageProxy.php?f=gepj.451b729a870062696011161/sdaolpUECMynit/12UGE&app=m&a=0&c=2ed88a397ba9c221f12dfdaaa040b3d2&ct=x&pn=gepj.elif&d=1" alt=""><img src="https://contentmanager.copernicus.org/fileStorageProxy.php?f=gepj.84a0a2aa870068796011161/sdaolpUECMynit/12UGE&app=m&a=0&c=b7eec20b0a3f0afb5c82791d9e72d449&ct=x&pn=gepj.elif&d=1" alt="">

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