scholarly journals Lava flow hazard map of Piton de la Fournaise volcano

2021 ◽  
Vol 21 (8) ◽  
pp. 2355-2377
Author(s):  
Magdalena Oryaëlle Chevrel ◽  
Massimiliano Favalli ◽  
Nicolas Villeneuve ◽  
Andrew J. L. Harris ◽  
Alessandro Fornaciai ◽  
...  
Keyword(s):  
Lava Flow ◽  
Hazard Assessment ◽  
Land Use Planning ◽  
18Th Century ◽  
Hot Spot ◽  
Hazard Map ◽  
Hazard Maps ◽  
Piton De La Fournaise ◽  
Lava Flow Hazard

Abstract. Piton de la Fournaise, situated on La Réunion island (France), is one of the most active hot spot basaltic shield volcanoes worldwide, experiencing at least two eruptions per year since the establishment of the volcanological observatory in 1979. Eruptions are typically fissure-fed and form extensive lava flow fields. About 95 % of some ∼ 250 historical events (since the first confidently dated eruption in 1708) have occurred inside an uninhabited horseshoe-shaped caldera (hereafter referred to as the Enclos), which is open to the ocean on its eastern side. Rarely (12 times since the 18th century), fissures have opened outside of the Enclos, where housing units, population centers, and infrastructure are at risk. In such a situation, lava flow hazard maps are a useful way of visualizing lava flow inundation probabilities over large areas. Here, we present the up-to-date lava flow hazard map for Piton de la Fournaise based on (i) vent distribution, (ii) lava flow recurrence times, (iii) statistics of lava flow lengths, and (iv) simulations of lava flow paths using the DOWNFLOW stochastic numerical model. The map of the entire volcano highlights the spatial distribution probability of future lava flow invasion for the medium to long term (years to decades). It shows that the most probable location for future lava flow is within the Enclos (where there are areas with up to 12 % probability), a location visited by more than 100 000 visitors every year. Outside of the Enclos, probabilities reach 0.5 % along the active rift zones. Although lava flow hazard occurrence in inhabited areas is deemed to be very low (< 0.1 %), it may be underestimated as our study is only based on post-18th century records and neglects older events. We also provide a series of lava flow hazard maps inside the Enclos, computed on a multi-temporal (i.e., regularly updated) topography. Although hazard distribution remains broadly the same over time, some changes are noticed throughout the analyzed periods due to improved digital elevation model (DEM) resolution, the high frequency of eruptions that constantly modifies the topography, and the lava flow dimensional characteristics and paths. The lava flow hazard map for Piton de la Fournaise presented here is reliable and trustworthy for long-term hazard assessment and land use planning and management. Specific hazard maps for short-term hazard assessment (e.g., for responding to volcanic crises) or considering the cycles of activity at the volcano and different event scenarios (i.e., events fed by different combinations of temporally evolving superficial and deep sources) are required for further assessment of affected areas in the future – especially by atypical but potentially extremely hazardous large-volume eruptions. At such an active site, our method supports the need for regular updates of DEMs and associated lava flow hazard maps if we are to be effective in keeping up to date with mitigation of the associated risks.

scholarly journals Lava flow hazard map of Piton de la Fournaise volcano 

2021 ◽  
Author(s):  
Oryaëlle Chevrel ◽  
Massimiliano Favalli ◽  
Villeneuve Nicolas ◽  
Andrew Harris ◽  
Alessandro Fornaciai ◽  
...  
Keyword(s):  
Lava Flow ◽  
18Th Century ◽  
Hot Spot ◽  
Hazard Map ◽  
Hazard Maps ◽  
Flow Paths ◽  
Piton De La Fournaise ◽  
Lava Flow Hazard ◽  
Multi Temporal ◽  
Deep Sources

&lt;p&gt;Piton de la Fournaise, situated on La Re&amp;#769;union Island (France), is one of the most active hot spot basaltic shield volcanoes worldwide, experiencing at least two eruptions per year since the establishment of the observatory in 1979. Eruptions are typically fissure-fed and form extensive lava flow fields. About 95 % of some ~250 historical events (since the first confidently dated eruption in 1708) have occurred inside an uninhabited horse-shoe shaped caldera (hereafter referred to as the Enclos) which is open to the ocean on its eastern side. Rarely (12 times since the 18th century), fissures have opened outside of the Enclos where housing units, population centers and infrastructure are at risk. In such a situation, lava flow hazard maps are a useful way of visualizing lava flow inundation probabilities over large areas. Here, we present a lava flow hazard map for Piton de la Fournaise volcano based on: i) vent distribution, ii) statistics of lava flow lengths, iii) lava flow recurrence times, and iv) simulations of lava flow paths across multi-temporal (i.e., regularly updated) topography using the DOWNFLOW stochastic numerical model. A map of the entire volcano highlights that the most probable (up to 12 %) location for future lava flow inundation is within the Enclos, where about 100,000 visitors are present each year. Hazard distribution changes throughout the analysis period due to the high frequency of eruptions that constantly modifies the vent opening distribution as well as the topography and the lava flow dimensional characteristics. Outside of the Enclos, probabilities reach 0.5 % along the well-defined rift zones and, although hazard occurrence in inhabited areas is deemed to be very low (&lt;0.1 %), it may be underestimated here, as our study is only based on post-18th century records and neglects cycles of activity at the volcano. Specific hazard maps considering different event scenarios (i.e., events fed by different combinations of temporally evolving superficial and deep sources) are required to better assess affected areas in the future &amp;#8211; especially by atypical, but potentially extremely hazardous, large volume eruptions. At such an active site, our method supports the need for regular updates of DEMs and associated lava flow hazard maps if we are to be effective in mitigating the associated risks.&lt;/p&gt;

scholarly journals Lava flow hazard map of Piton de la Fournaise volcano

2020 ◽  
Author(s):  
Magdalena Oryaëlle Chevrel ◽  
Massimiliano Favalli ◽  
Nicolas Villeneuve ◽  
Andrew J. L. Harris ◽  
Alessandro Fornaciai ◽  
...  
Keyword(s):  
Lava Flow ◽  
18Th Century ◽  
Hot Spot ◽  
Hazard Map ◽  
Flow Paths ◽  
Piton De La Fournaise ◽  
Lava Flow Hazard ◽  
Multi Temporal ◽  
La Réunion Island ◽  
Hazard Distribution

Abstract. Piton de la Fournaise, situated on La Réunion Island (France), is one of the most active hot spot basaltic shield volcanoes worldwide, experiencing at least two eruptions per year since the establishment of the observatory in 1979. Eruptions are typically fissure-fed and form extensive lava flow fields. About 95 % of some ~250 historical events (since the first confidently dated eruption in 1708) have occurred inside an uninhabited horse-shoe shaped caldera (hereafter referred to as the Enclos) which is open to the ocean on its eastern side. Rarely (12 times since the 18th century), fissures have opened outside of the Enclos where housing units, population centers and infrastructure are at risk. In such a situation, lava flow hazard maps are a useful way of visualizing lava flow inundation probabilities over large areas. Here, we present a lava flow hazard map for Piton de la Fournaise volcano based on: i) vent distribution, ii) statistics of lava flow lengths, iii) lava flow recurrence times, and iv) simulations of lava flow paths across multi-temporal (i.e., regularly updated) topography using the DOWNFLOW stochastic numerical model. A map of the entire volcano highlights that the most probable (up to 12 %) location for future lava flow inundation is within the Enclos, where about 100,000 visitors are present each year. Hazard distribution changes throughout the analysis period due to the high frequency of eruptions that constantly modifies the vent opening distribution as well as the topography and the lava flow dimensional characteristics. Outside of the Enclos, probabilities reach 0.5 % along the well-defined rift zones and, although hazard occurrence in inhabited areas is deemed to be very low (

Fast short-term lava flow hazard assessment with graph theory

2020 ◽  
Author(s):  
Veronica Centorrino ◽  
Giuseppe Bilotta ◽  
Annalisa Cappello ◽  
Gaetana Ganci ◽  
Claudia Corradino ◽  
...  
Keyword(s):  
Graph Theory ◽  
Lava Flow ◽  
Graph Representation ◽  
Computational Time ◽  
Hazard Map ◽  
Short Term ◽  
Flow Paths ◽  
Lava Flow Hazard ◽  
Mt Etna

&lt;p&gt;We explore the use of graph theory to assess short-term hazard of lava flow inundation, with Mt Etna as a case study. In the preparation stage, we convert into a graph the long-term hazard map produced using about 30,000 possible eruptive scenarios calculated by simulating lava flow paths with the physics-based MAGFLOW model. Cells in the original DEM-based representation are merged into graph vertices if reached by the same scenarios, and for each pair of vertices, a directed edge is defined, with an associated lava conductance (probability of lava flowing from one vertex to the other) computed from the number of scenarios that reach both the start and end vertex. In the application stage, the graph representation can be used to extract short-term lava flow hazard maps in case of unrest. When a potential vent opening area is identified e.g. from monitoring data, the corresponding vertices in the graph are activated, and the information about lava inundation probability is iteratively propagated to neighboring vertices through the edges, weighted according to the associated lava conductance. This allows quick identification of potentially inundated areas with little computational time. A comparison with the deterministic approach of subsetting and recomputing the weights in the long-term hazard map is also presented to illustrate benefits and downsides of the graph-based approach.&lt;/p&gt;

scholarly journals Assessing qualitative long-term volcanic hazards at Lanzarote Island (Canary Islands)

2017 ◽  
Vol 17 (7) ◽  
pp. 1145-1157 ◽  
Author(s):  
Laura Becerril ◽  
Joan Martí ◽  
Stefania Bartolini ◽  
Adelina Geyer
Keyword(s):  
Canary Islands ◽  
Hazard Assessment ◽  
Land Use Planning ◽  
Volcanic Hazards ◽  
Economic Losses ◽  
Hazard Evaluation ◽  
Hazard Maps ◽  
Emergency Plans ◽  
Definition Of

Abstract. Conducting long-term hazard assessment in active volcanic areas is of primary importance for land-use planning and defining emergency plans able to be applied in case of a crisis. A definition of scenario hazard maps helps to mitigate the consequences of future eruptions by anticipating the events that may occur. Lanzarote is an active volcanic island that has hosted the largest (>  1.5 km3 DRE) and longest (6 years) eruption, the Timanfaya eruption (1730–1736), on the Canary Islands in historical times (last 600 years). This eruption brought severe economic losses and forced local people to migrate. In spite of all these facts, no comprehensive hazard assessment or hazard maps have been developed for the island. In this work, we present an integrated long-term volcanic hazard evaluation using a systematic methodology that includes spatial analysis and simulations of the most probable eruptive scenarios.

Supplementary material to "Lava flow hazard map of Piton de la Fournaise volcano"

2020 ◽  
Author(s):  
Magdalena Oryaëlle Chevrel ◽  
Massimiliano Favalli ◽  
Nicolas Villeneuve ◽  
Andrew J. L. Harris ◽  
Alessandro Fornaciai ◽  
...  
Keyword(s):  
Lava Flow ◽  
Hazard Map ◽  
Piton De La Fournaise ◽  
Lava Flow Hazard ◽  
Supplementary Material

Probabilistic Tephra Hazard Assessment of Campi Flegrei, Italy

2021 ◽  
Author(s):  
Beatriz Martínez Montesinos ◽  
Manuel Titos ◽  
Laura Sandri ◽  
Sara Barsotti ◽  
Giovanni Macedonio ◽  
...  
Keyword(s):  
Hazard Assessment ◽  
Wide Spectrum ◽  
Numerical Code ◽  
Campi Flegrei ◽  
Computational Domain ◽  
Event Tree ◽  
Hazard Maps ◽  
Event Tree Analysis ◽  
Short And Long Term

&lt;p&gt;Campi Flegrei is an active volcano located in one of the most densely inhabited areas in Europe and under high-traffic air routes. There, the Vesuvius Observatory&amp;#8217;s surveillance system, which continuously monitors volcanic seismicity, soil deformations and gas emissions, highlights some variations in the state of the volcanic activity. It is well known that fragmented magma injected into the atmosphere during an explosive volcanic eruption poses a threat to human lives and air-traffic. For this reason, powerful tools and computational resources to generate extensive and high-resolution hazard maps taking into account a wide spectrum of events, including those of low probability but high impact, are important to provide decision makers with quality information to develop short- and long- term emergency plans. To this end, in the framework of the Center of Excellence for Exascale in Solid Earth (ChEESE), we show the potential of HPC in Probabilistic Volcanic Hazard Assessment. On the one hand, using the ChEESE's flagship Fall3D numerical code and taking advance of the PRACE-awarded resources at CEA/TGCC-HPC facility in France, we perform thousands of simulations of tephra deposition and airborne ash concentration at different flight levels exploring the natural variability and uncertainty on the eruptive conditions on a 3D-grid covering a 2 km-resolution 2000 km x 2000 km computational domain. On the other hand, we create short- and long-term workflows, by updating current Bayesian-Event-Tree-Analysis-based prototype tools, to make them capable of analyze the large amount of information generated by the Fall3D simulations that finally gives rise to the hazard maps for Campi Flegrei.&lt;/p&gt;

scholarly journals A method for multi-hazard mapping in poorly known volcanic areas: an example from Kanlaon (Philippines)

2013 ◽  
Vol 13 (8) ◽  
pp. 1929-1943 ◽  
Author(s):  
M. Neri ◽  
G. Le Cozannet ◽  
P. Thierry ◽  
C. Bignami ◽  
J. Ruch
Keyword(s):  
Land Use Planning ◽  
Volcanic Hazards ◽  
Mapping Method ◽  
Hazard Mapping ◽  
Hazard Map ◽  
Event Tree ◽  
Planning Decisions ◽  
Civil Defence ◽  
Term Data

Abstract. Hazard mapping in poorly known volcanic areas is complex since much evidence of volcanic and non-volcanic hazards is often hidden by vegetation and alteration. In this paper, we propose a semi-quantitative method based on hazard event tree and multi-hazard map constructions developed in the frame of the FP7 MIAVITA project. We applied this method to the Kanlaon volcano (Philippines), which is characterized by poor geologic and historical records. We combine updated geological (long-term) and historical (short-term) data, building an event tree for the main types of hazardous events at Kanlaon and their potential frequencies. We then propose an updated multi-hazard map for Kanlaon, which may serve as a working base map in the case of future unrest. The obtained results extend the information already contained in previous volcanic hazard maps of Kanlaon, highlighting (i) an extensive, potentially active ~5 km long summit area striking north–south, (ii) new morphological features on the eastern flank of the volcano, prone to receiving volcanic products expanding from the summit, and (iii) important riverbeds that may potentially accumulate devastating mudflows. This preliminary study constitutes a basis that may help local civil defence authorities in making more informed land use planning decisions and in anticipating future risk/hazards at Kanlaon. This multi-hazard mapping method may also be applied to other poorly known active volcanoes.

scholarly journals Retrospective validation of a lava-flow hazard map for Mount Etna volcano

2011 ◽  
Vol 54 (5) ◽  
Author(s):  
Annalisa Cappello ◽  
Annamaria Vicari ◽  
Ciro Del Negro
Keyword(s):  
Lava Flow ◽  
Mount Etna ◽  
Hazard Map ◽  
Etna Volcano ◽  
Lava Flow Hazard

Towards a quantified and global landslide hazard assessment for New-Caledonia (South Pacific) in a regulatory mapping context

2021 ◽  
Author(s):  
Bastien Colas ◽  
Yannick Thiery ◽  
Yaël Guyomard ◽  
Mathieu Mengin ◽  
Olivier Monge ◽  
...  
Keyword(s):  
Land Use ◽  
Hazard Assessment ◽  
Land Use Planning ◽  
Debris Flows ◽  
New Caledonia ◽  
Statistical Tests ◽  
South Pacific ◽  
Landslide Hazard ◽  
Hazard Maps ◽  
Landslide Hazard Assessment

&lt;p&gt;Requiring spatial and temporal quantified information on landslide hazard over a large area is a prerequisite to forecast them. However, in many cases, the quantification remains partial, because of a lack of information on the phenomena, on predisposing and triggering factors or because the scientific approaches used in research domain are complex to apply in a regulatory framework. Thus, in this context, for many sites and end-users, the documents produced by empirical methods are used, without quantification of hazards.&lt;/p&gt;&lt;p&gt;In 2019, a collaboration between the DIMENC Geological Survey Service of New-Caledonia (South-Pacific) and the BRGM planed the development of a global methodology of landslide hazard assessment at the 1:25,000 scale of work according to the recommendations of the JTC-1. Indeed, landslide hazard in New Caledonia is insufficiently assessed and few taken into account in land-use planning. However, this large mountainous island is regularly affected by different type of instabilities (i.e. rock-falls; rock-slides; slides; debris-flows) due to intense rainfalls. The consequences can be material and human, as in 2016 for the municipality of Houa&amp;#239;lou, where debris-flows occurred, inducing 5 deaths, 3 missing persons, 8 injuries along with large material damages. Few heuristic landslide hazard maps based on expert opinion are available, but the methodology is not homogeneous and harmonized. Therefore, even if these maps constitute a solid base of knowledge, their valorization for land use planning remains difficult.&lt;/p&gt;&lt;p&gt;To overcome these shortcomings, the methodology chosen is quantitative, taking into account the susceptibility of the territory (i.e. spatial probability of phenomena occurrence with discrimination of initiation and run-out), the temporal probability of occurrence (i.e. from diachronic analyses) and the phenomena intensity (i.e. through the considered velocity of runout and the potential of induced damages). The methodology is declined by type of phenomena and is based on a comprehensive inventory. Six main steps are defined with:&lt;/p&gt;&lt;ul&gt;&lt;li&gt;An inventory of the events by visual remote sensing and field observations;&lt;/li&gt; &lt;li&gt;Discriminated mapping of bedrock and surficial formations (i.e. regolith: weathered formations and gravitational deposits);&lt;/li&gt; &lt;li&gt;Computation of each landslide initiation susceptibility by a bivariate method;&lt;/li&gt; &lt;li&gt;Integration of the temporal occurrence probability;&lt;/li&gt; &lt;li&gt;Computation of the phenomena runout by a numerical approach taking into account the reach angle;&lt;/li&gt; &lt;li&gt;Integration of the intensity of the phenomena according to the estimated volumes and/or velocity to quantify landslide hazard.&lt;/li&gt; &lt;/ul&gt;&lt;p&gt;The classes of spatial and temporal probabilities are based on the JTC-1 agreement and allow obtaining quantified hazard maps. The validation of the results is performed by a field validation, by phenomena not used for the computations, and by statistical tests. The method is tested in the municipality of Mont-Dore (643 km&amp;#178;), which was heavily impacted in 1988 by cyclone 'Anne'. Beyond the fact that the methodology will be applied throughout the territory in an operational framework and will allow the adaptation of local planning, the project allows the improvement of:&lt;/p&gt;&lt;ul&gt;&lt;li&gt;Knowledge of the different kind of landslides in a volcano-sedimentary and metamorphic context strongly weathered;&lt;/li&gt; &lt;li&gt;Knowledge of the regolith, which newly integrated for this type of analysis for the island&amp;#8217;s municipalities.&lt;/li&gt; &lt;/ul&gt;

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