Fall-out and deposition of volcanic ash during the 1979 explosive eruption of the soufriere of St. Vincent

Brazier, S.; Davis, A. N.; Sigurdsson, Haraldur; Sparks, R. S. J.

doi:10.1016/0377-0273(82)90069-5

Cited by 72 publications

(37 citation statements)

References 16 publications

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“…During the 1979 eruption of Soufriere St. Vincent, fallout of 'dry' AP1 aggregates (which broke on impact) and wet AP1 and AP3 aggregates (which splashed or flattened on deposition) occurred on separate occasions in proximal regions (< 9 km) from plumes that reached ~18 km height (Brazier et al, 1982). More observations of aggregate morphology alongside quantitative measurement of environmental parameters are needed to discriminate the effect on aggregation rate.…”

Section: Aggregation Within Ash Plumes: Conditions and Downwind Changesmentioning

confidence: 99%

A review of volcanic ash aggregation

Brown

Bonadonna

Durant

2012

Physics and Chemistry of the Earth, Parts A/B/C

230

298

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. (2012) 'A review of volcanic ash aggregation.', Physics and chemistry of the earth, parts A/B/C., 45-46 . pp. 65-78. Further information on publisher's website:http://dx.doi.org/10.1016/j.pce. 2011.11.001 Publisher's copyright statement:Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. AbstractMost volcanic ash particles with diameters < 63 µm settle from eruption clouds as particle aggregates that cumulatively have larger sizes, lower densities, and higher terminal fall velocities than individual constituent particles. Particle aggregation reduces the atmospheric residence time of fine ash, which results in a proportional increase in fine ash fallout within 10s km to 100s km from the volcano and a reduction in airborne fine ash mass concentrations 1000s km from the volcano. Aggregate characteristics vary with distance from the volcano: proximal aggregates are typically larger (up to cm size) with concentric structures, while distal aggregates are typically smaller (sub-millimetre size). Particles comprising ash aggregates are bound through hydro-bonds (liquid and ice water) and electrostatic forces, and the rate of particle aggregation correlates with cloud liquid water availability. Eruption source parameters (including initial particle size distribution, erupted mass, eruption column height, cloud water content and temperature) and the eruption plume temperature lapse rate, coupled with the environmental parameters, determines the type and spatiotemporal distribution of aggregates. Field studies, lab experiments and modelling investigations have already provided important insights on the process of particle aggregation. However, new integrated observations that combine remote sensing studies of 2 ash clouds with field measurement and sampling, and lab experiments are required to fill current gaps in knowledge surrounding the theory of ash aggregate formation. Abstract word count: 222

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Section: Aggregation Within Ash Plumes: Conditions and Downwind Changesmentioning

confidence: 99%

A review of volcanic ash aggregation

Brown

Bonadonna

Durant

2012

Physics and Chemistry of the Earth, Parts A/B/C

230

298

View full text Add to dashboard Cite

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“…Until recently, ash particles were commonly modeled as spheres (Brazier et al, 1982;Carey and Sigurdsson, 1982;Suzuki, 1983;Armienti et al, 1988;Glaze and Self, 1991;Sparks et al, 1992;Hurst and Turner, 1999;Bonadonna et al, 2005), mainly because of the difficulty of adequately determining particle shape (Folch, 2012). Such an assumption may result in misinterpretations and errors in the description of volcanic plume behavior.…”

Section: Introduction and Previous Workmentioning

confidence: 99%

High-resolution 3D analyses of the shape and internal constituents of small volcanic ash particles: The contribution of SEM micro-computed tomography (SEM micro-CT)

Vonlanthen

Rausch

Ketcham

et al. 2015

Journal of Volcanology and Geothermal Research

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The morphology of small volcanic ash particles is fundamental to our understanding of magma fragmentation, and in transport modeling of volcanic plumes and clouds. Until recently, the analysis of 3D features in small objects (b250 μm) was either restricted to extrapolations from 2D approaches, partial stereo-imaging, or CT methods having limited spatial resolution and/or accessibility. In this study, an X-ray computed-tomography technique known as SEM micro-CT, also called 3D X-ray ultramicroscopy (3D XuM), was used to investigate the 3D morphology of small volcanic ash particles (125-250 μm sieve fraction), as well as their vesicle and microcrystal distribution. The samples were selected from four stratigraphically well-established tephra layers of the Meerfelder Maar (West Eifel Volcanic Field, Germany). Resolution tests performed on a Beametr v1 pattern sample along with Monte Carlo simulations of X-ray emission volumes indicated that a spatial resolution of 0.65 μm was obtained for X-ray shadow projections using a standard thermionic SEM and a bulk brass target as X-ray source. Analysis of a smaller volcanic ash particle (64-125 μm sieve fraction) showed that features with volumes N 20 μm 3 (~3.5 μm in diameter) can be successfully reconstructed and quantified. In addition, new functionalities of the Blob3D software were developed to allow the particle shape factors frequently used as input parameters in ash transport and dispersion models to be calculated. This study indicates that SEM micro-CT is very well suited to quantify the various aspects of shape in fine volcanic ash, and potentially also to investigate the 3D morphology and internal structure of any object b 0.1 mm 3 .

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“…Locally a continuous ash blanket may extend up to 9 km in all directions. Within 2.5 km of the vent, in eruptions of the scale of 1979, up to 45 cm may accumulate (Brazier et al, 1982). This may decrease to 45 mm up to 4 km from the crater rim.…”

Section: Expected Hazards and Hazard Map Developmentmentioning

confidence: 99%

“…With increasing magnitude, collapse of large dense columns (>>20 km) may lead to flows that surmount the Somma Ridge and follow the valleys rivers to the north and northeast coast (moderate pyroclastic flow/surge hazard zones in Figure 4A). Pyroclastic surges will tend to affect areas in all azimuths from the crater since they are less constrained by topography; eruptions of 1979 magnitude may generate surge deposits ≥0.5 m thick within 2 km of the crater rim in all directions (Brazier et al, 1982). With larger eruptions the area affected may increase to a possible maximum of 5 km (Anderson and Flett, 1903).…”

Section: Expected Hazards and Hazard Map Developmentmentioning

confidence: 99%

Integrating Volcanic Hazard Data in a Systematic Approach to Develop Volcanic Hazard Maps in the Lesser Antilles

Lindsay

Robertson

2018

Front. Earth Sci.

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We report on the process of generating the first suite of integrated volcanic hazard zonation maps for the islands of Dominica, Grenada (including Kick 'em Jenny and Ronde/Caille), Nevis, Saba, St. Eustatius, St. Kitts, Saint Lucia, and St Vincent in the Lesser Antilles. We developed a systematic approach that accommodated the range in prior knowledge of the volcanoes in the region. A first-order hazard assessment for each island was used to develop one or more scenario(s) of likely future activity, for which scenario-based hazard maps were generated. For the most-likely scenario on each island we also produced a poster-sized integrated volcanic hazard zonation map, which combined the individual hazardous phenomena depicted in the scenario-based hazard maps into integrated hazard zones. We document the philosophy behind the generation of this suite of maps, and the method by which hazard information was combined to create integrated hazard zonation maps, and illustrate our approach through a case study of St. Vincent. We also outline some of the challenges we faced using this approach, and the lessons we have learned by observing how stakeholders have interacted with the maps over the past ∼10 years. Based on our experience, we recommend that future map makers involve stakeholders in the entire map generation process, especially when making design choices such as type of base map, use of colour and gradational boundaries, and indeed what to depict on the map. We also recommend careful consideration of how to evaluate and depict offshore hazard of island volcanoes, and recommend computer-assisted modelling of all phenomena to generate more realistic hazard footprints. Finally, although our systematic approach to integrating individual hazard data into zones generally worked well, we suggest that a better approach might be to treat the integration of hazards on a case-by-case basis to ensure the final product meets map users' needs. We hope that the documentation of our experience might be useful for other map makers to take into account when creating new or updating existing maps.

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Fall-out and deposition of volcanic ash during the 1979 explosive eruption of the soufriere of St. Vincent

Cited by 72 publications

References 16 publications

A review of volcanic ash aggregation

A review of volcanic ash aggregation

High-resolution 3D analyses of the shape and internal constituents of small volcanic ash particles: The contribution of SEM micro-computed tomography (SEM micro-CT)

Integrating Volcanic Hazard Data in a Systematic Approach to Develop Volcanic Hazard Maps in the Lesser Antilles

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