Eifel maars: Quantitative shape characterization of juvenile ash particles (Eifel Volcanic Field, Germany)

Rausch, Juanita; Grobéty, Bernard; Vonlanthen, Pierre

doi:10.1016/j.jvolgeores.2014.11.008

Cited by 28 publications

(33 citation statements)

References 62 publications

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“…The well-exposed MFM deposits crop out in the Leyendecker quarry, about 400 m west of the MFM crater rim (s. Appendix 1 in Rausch et al, 2015). The outcrop consists of a 19-23 m thick maar sequence representing the medial to proximal facies of the eruption, as testified by the large volcanic ejecta (blocks up to 1 m in diameter) present within the deposit.…”

Section: Methodsmentioning

confidence: 99%

“…Volcanic ash particles were sampled in four stratigraphically wellconstrained layers: MFM03, MFM20, MFM40, and MFM45 (s. Table 1 in Rausch et al, 2015). MFM03 is a 6-14 cm thick well-sorted layer made of highly vesicular black scoria lapilli, interpreted as magmatic fallout.…”

Section: Methodsmentioning

confidence: 99%

“…The present paper, along with the paper of Rausch et al (2015), reports the first applied study on volcanic ash particles based on full 3D SEM micro-CT analyses. This novel application allows for quantitative 3D morphological analysis of the shape and internal constituents of small objects with potentially sub-micron resolution, which makes it a method of choice for the analysis of volcanic ash.…”

Section: Introduction and Previous Workmentioning

confidence: 99%

“…This novel application allows for quantitative 3D morphological analysis of the shape and internal constituents of small objects with potentially sub-micron resolution, which makes it a method of choice for the analysis of volcanic ash. The present contribution focuses on the methodology of SEM micro-CT, with a special attention to the scope and limitations of the technique when applied to volcanic ash, whereas in the paper of Rausch et al (2015) the morphological data have been used along with fractal analysis to investigate the significance and origin of volatiles in Eifel maar volcanism. Beyond the characterization of ash particles, these two contributions open new perspectives in various fields of Earth and materials sciences for which quantification of 3D features in small objects is required.…”

Section: Introduction and Previous Workmentioning

confidence: 99%

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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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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introduction and Previous Workmentioning

confidence: 99%

Section: Introduction and Previous Workmentioning

confidence: 99%

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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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“…From a microscopic perspective, the relation between particle morphology and eruptive and transport mechanisms has been abundantly explored (e.g., Dellino and Liotino 2002;Ersoy et al 2006Ersoy et al , 2008Heiken and Wohletz 1985;Leibrandt and Le Pennec 2015;Liu et al 2015;Rausch et al 2015;Riley et al 2003;Sheridan and Kortemeier 1987;Sheridan and Marshall 1983;Vonlanthen et al 2015). Heiken (1972) considered that the shape of particles in the ash size range is mostly dependent on the shape of magmatic gas bubbles at the moment of fragmentation: flat and platy shards arise from broken vesicle walls, and droplet shapes are produced from low viscosity magma where the effect of surface tension is likely to become more important.…”

Section: Introductionmentioning

confidence: 99%

Mechanism of formation of volcanic bombs: insights from a pilot study of anisotropy of magnetic susceptibility and preliminary assessment of analytical models

Cañón‐Tapia

2017

Bull Volcanol

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Volcanic bombs and achneliths are a special type of pyroclastic fragments formed by mildly explosive volcanic eruptions. Models explaining the general shapes of those particles can be divided in two broad categories. The most popular envisages the acquisition of shapes of volcanic bombs as the result of the rush of air acting on a fluid clot during flight, and it includes many variants. The less commonly quoted model envisages their shapes as the result of forces acting at the moment of ejection of liquid from the magma pool in the conduit, experiencing an almost negligible modification through its travel through air. Quantitative evidence supporting either of those two models is limited. In this work, I explore the extent to which the anisotropy of magnetic susceptibility (AMS) might be useful in the study of mechanisms of formation of volcanic bombs by comparing measurements made on two spindle and two bread-crusted bombs. The results of this pilot study reveal that the degree of anisotropy of spindle bombs is larger, and their principal susceptibility axes are better clustered than on bread-crusted bombs. Also, the orientation of the principal susceptibility axes is consistent with two specific models (one of the in-flight variants and the general ejection model). Consequently, the reported AMS measurements, albeit limited in number, indicate that it is reasonable to focus attention on only two specific models to explain the acquisition of the shapes of volcanic bombs. Based on a parallel theoretical assessment of analytical models, a third alternative is outlined, envisaging volcanic bomb formation as a two-stage process that involves the bursting of large (~m) gas bubbles on the surface of a magma pond. The new model advanced here is also consistent with the reported AMS results, and constitutes a working hypothesis that should be tested by future studies richer in data. Fortunately, since this work also establishes that AMS can be used to determine magnetic fabric in small size samples, the possibility to expand this study to a larger collection of bombs is granted.

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Monitoring of Eruptive Products: Deposits Associated with Pyroclastic Fallout

Gurioli¹,

Tadini²,

Thivet³

et al. 2022

Hazards and Monitoring of Volcanic Activity 3

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Eifel maars: Quantitative shape characterization of juvenile ash particles (Eifel Volcanic Field, Germany)

Cited by 28 publications

References 62 publications

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)

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)

Mechanism of formation of volcanic bombs: insights from a pilot study of anisotropy of magnetic susceptibility and preliminary assessment of analytical models

Monitoring of Eruptive Products: Deposits Associated with Pyroclastic Fallout

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