Examining the impact of lahars on buildings using numerical modelling

Mead, Stuart; Magill, Christina; Lemiale, Vincent; Thouret, Jean‐Claude; Prakash, Mahesh

doi:10.5194/nhess-17-703-2017

Cited by 17 publications

(40 citation statements)

References 40 publications

(88 reference statements)

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“…Several studies have examined the vulnerability of buildings with regard to the impact of a pyroclastic flow or lahar (Alberico et al, 2002; Dagá et al, 2018; Jenkins et al, 2015; Mead et al, 2017; Petrazzuoli & Zuccaro, 2004; Spence et al, 2004; Thouret et al, 2013), mostly based on analysis of damage of past eruptions, although some also include casualty information, physical and/or probabilistic models. Long‐term loss assessments are developed in Spence et al (2004) for pyroclastic flows and Mead et al (2017) for lahars, based on numerical models, exposure, and vulnerability analyses. Lava flows are easier to address in terms of operational impact forecasting as propagation rates are generally slow (lava flow speeds >4 km/hr are rare) and vulnerability is roughly binary (0 or 1, i.e., complete destruction if a building is inundated by lava), so that hazard maps can be easily convolved with exposure maps into impact forecasts.…”

Section: State Of the Art Of Impact Forecastingmentioning

confidence: 99%

“…Studies on the impact of tephra fallout usually perform some form of vulnerability assessment (e.g., of buildings or flight paths), and both probabilistic loss models and empirical data are used to build fragility functions. Several studies have examined the vulnerability of buildings with regard to the impact of a pyroclastic flow or lahar (Alberico et al, 2002; Dagá et al, 2018; Jenkins et al, 2015; Mead et al, 2017; Petrazzuoli & Zuccaro, 2004; Spence et al, 2004; Thouret et al, 2013), mostly based on analysis of damage of past eruptions, although some also include casualty information, physical and/or probabilistic models. Long‐term loss assessments are developed in Spence et al (2004) for pyroclastic flows and Mead et al (2017) for lahars, based on numerical models, exposure, and vulnerability analyses.…”

Section: State Of the Art Of Impact Forecastingmentioning

confidence: 99%

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Impact Forecasting to Support Emergency Management of Natural Hazards

Merz

Kuhlicke

Kunz

et al. 2020

Reviews of Geophysics

111

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Forecasting and early warning systems are important investments to protect lives, properties, and livelihood. While early warning systems are frequently used to predict the magnitude, location, and timing of potentially damaging events, these systems rarely provide impact estimates, such as the expected amount and distribution of physical damage, human consequences, disruption of services, or financial loss. Complementing early warning systems with impact forecasts has a twofold advantage: It would provide decision makers with richer information to take informed decisions about emergency measures and focus the attention of different disciplines on a common target. This would allow capitalizing on synergies between different disciplines and boosting the development of multihazard early warning systems. This review discusses the state of the art in impact forecasting for a wide range of natural hazards. We outline the added value of impact-based warnings compared to hazard forecasting for the emergency phase, indicate challenges and pitfalls, and synthesize the review results across hazard types most relevant for Europe. Plain Language Summary Forecasting and early warning systems are important investments to protect lives, properties and livelihood. While such systems are frequently used to predict the magnitude, location, and timing of potentially damaging events, they rarely provide impact estimates, such as the expected physical damage, human consequences, disruption of services, or financial loss. Extending hazard forecast systems to include impact estimates promises many benefits for the emergency phase, for instance, for organizing evacuations. We review and compare the state of the art of impact forecasting across a wide range of natural hazards and outline opportunities and key challenges for research and development of impact forecasting.

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Section: State Of the Art Of Impact Forecastingmentioning

confidence: 99%

Section: State Of the Art Of Impact Forecastingmentioning

confidence: 99%

Impact Forecasting to Support Emergency Management of Natural Hazards

Merz

Kuhlicke

Kunz

et al. 2020

Reviews of Geophysics

111

View full text Add to dashboard Cite

show abstract

“…The risk for such overbank processes and spreading of unconfined PCs inside Arequipa should then be refined and the "high hazard zone" of the hazard map extended accordingly. In order to help further investigate such overbank PC hazards in the city of Arequipa, future work will involve small-scale, high-resolution numerical modeling of valley-confined PCs performed over a very high resolution (<1 m) DSM along short reaches (few hundreds of meters long) of the San Lázaro and Huarangal-MM channels, similar to the recent work of Mead et al (2017) to estimate building vulnerability from lahars in Q. Dahlia, a tributary to the latter channel. Robust estimates of the potential range of local mass fluxes and velocities of valley-confined PCs for each channel segment are critical for correctly assessing numerically overbank PC processes at such fine-scale level.…”

Section: Considerations For Future Hazard Assessment Of Pyroclastic Cmentioning

confidence: 99%

New Insights Into the 2070calyrBP Pyroclastic Currents at El Misti Volcano (Peru) From Field Investigations, Satellite Imagery and Probabilistic Modeling

et al. 2020

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Pyroclastic currents (PCs) are the most challenging volcanic hazards for disaster planners in populated areas around volcanoes. "El Misti" volcano (5,825 m above sea level), located only 17 km from the city center of Arequipa (>1.1 million inhabitants), South Peru, has produced small-to-moderate volume (<1 km 3) PCs with a frequency of 2,000-4,000 years over the past 50 kyr. The most recent Plinian eruption dated at 2070 cal yr BP (VEI 4) has been selected as one of the reference events for the hazard assessment and risk mitigation plan of Arequipa. Associated pumice-and lithic-rich PC deposits were emplaced from at least four phases of column-collapse into the radial valleys draining the volcano as far as 13 km toward the city. Field mapping and stratigraphic surveys conducted in seven valleys affected by the 2070 cal yr BP PCs were combined with a new high-resolution (2 m) digital surface model of the volcano to better estimate the distribution of individual PC volumes. Such data acquisition is particularly critical for two of these valleys (San Lázaro and Huarangal-Mariano Melgar) for which the medial and distal reaches now cross the suburbs of Arequipa. The total area covered by the PC deposits is estimated at 141 km 2 for a total bulk volume estimated at 406 ± 140 × 10 6 m 3. These volumes were used as input parameters to better calibrate probabilistic numerical simulations of future similar PC events using the two-layer VolcFlow model and assess the impacts of both the concentrated and dilute portions of these currents in the San Lázaro and Huarangal valleys. We discuss probability values of PC inundation obtained from these simulations both in terms of their implications for the dynamics of such hazardous PCs at El Misti and for their integration into its current multi-hazard assessment. Modeling results demonstrate that the risk of overbank processes and spreading of unconfined PCs inside Arequipa should be refined. This multidisciplinary study aims to help the civil authorities' understanding of the likely effects of PCs associated with a similar VEI 4 eruption of El Misti on the urban area of Arequipa.

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“…Global comparisons characterise a mass flow into single, easy to interpret metrics (e.g. length of flow, area inundated; Charbonnier et al, 2017;Mergili et al, 2017) but can disguise both spatial and temporal divergent behaviour (Bennett et al, 2013). Local comparisons of model performance typically utilise a confusion matrix (Bennett et al, 2013;Charbonnier et al, 2017;Mergili et al, 2017) to classify proportions of correctly or incorrectly simulated data points, in which spatial accuracy of simulators can be evaluated by comparing pixel pairs on a map (Wealands et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

Quantifying location error to define uncertainty in volcanic mass flow hazard simulations

Mead

Procter

Keresztúri

2021

Nat. Hazards Earth Syst. Sci.

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Abstract. The use of mass flow simulations in volcanic hazard zonation and mapping is often limited by model complexity (i.e. uncertainty in correct values of model parameters), a lack of model uncertainty quantification, and limited approaches to incorporate this uncertainty into hazard maps. When quantified, mass flow simulation errors are typically evaluated on a pixel-pair basis, using the difference between simulated and observed (“actual”) map-cell values to evaluate the performance of a model. However, these comparisons conflate location and quantification errors, neglecting possible spatial autocorrelation of evaluated errors. As a result, model performance assessments typically yield moderate accuracy values. In this paper, similarly moderate accuracy values were found in a performance assessment of three depth-averaged numerical models using the 2012 debris avalanche from the Upper Te Maari crater, Tongariro Volcano, as a benchmark. To provide a fairer assessment of performance and evaluate spatial covariance of errors, we use a fuzzy set approach to indicate the proximity of similarly valued map cells. This “fuzzification” of simulated results yields improvements in targeted performance metrics relative to a length scale parameter at the expense of decreases in opposing metrics (e.g. fewer false negatives result in more false positives) and a reduction in resolution. The use of this approach to generate hazard zones incorporating the identified uncertainty and associated trade-offs is demonstrated and indicates a potential use for informed stakeholders by reducing the complexity of uncertainty estimation and supporting decision-making from simulated data.

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Examining the impact of lahars on buildings using numerical modelling

Abstract: International audienc

Cited by 17 publications

References 40 publications

Impact Forecasting to Support Emergency Management of Natural Hazards

Impact Forecasting to Support Emergency Management of Natural Hazards

New Insights Into the 2070calyrBP Pyroclastic Currents at El Misti Volcano (Peru) From Field Investigations, Satellite Imagery and Probabilistic Modeling

Quantifying location error to define uncertainty in volcanic mass flow hazard simulations

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