Charge measurements on particle fallout from a volcanic plume

Gilbert, Jennifer; Lane, S. J.; Sparks, R. S. J.; Koyaguchi, Takehiro

doi:10.1038/349598a0

Cited by 127 publications

(110 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The Faraday cup experiments produced silicate particles with specific net charges similar to those previously measured on ashfall [Hatakeyama, 1958;Gilbert et al, 1991;Miura et al, 1995]. Particles produced by sample impacts held net charges substantially greater than those produced during the friction-dominated rotational experiments.…”

Section: Discussionsupporting

confidence: 57%

Volcanic plume electrification: Experimental investigation of a fracture‐charging mechanism

James¹,

Lane²,

Gilbert³

2000

J. Geophys. Res.

Self Cite

131

View full text Add to dashboard Cite

Abstract. Although ashfall from particulate volcanic plumes is known to be highly electrically charged, little is known about the charging mechanism. We describe experiments designed to investigate the particle charges generated from the fracture of pumice. Small silicate particles were produced in the laboratory during collisions between two samples cut from pumice clasts. The net charge magnitudes detected on these particles are similar to those previously measured on ashfall from volcanic plumes (-10 's to 10 -6 C kg-•). This net charge is also shown to be the result of a small imbalance between the sums of individual particle charges of both polarities, which are up to several orders of magnitude larger than the net charge. The magnitude of both the net and single polarity specific charges were only weakly affected by changes of relative humidity, but single polarity charges increased steadily with increasing sample impact velocities. The dominant charging process during the experiments was that of material fracture. The charging mechanism is thus interpreted to be fractoemission (the release of nuclear particles from fresh crack surfaces) occurring during the production of the silicate particles. This implies that the electrification of volcanic plumes could be the result of brittle fragmentation of magma or pumice clasts within the upper regions of the conduit and in the jet region of the plume.

show abstract

Section: Discussionsupporting

confidence: 57%

Volcanic plume electrification: Experimental investigation of a fracture‐charging mechanism

James¹,

Lane²,

Gilbert³

2000

J. Geophys. Res.

Self Cite

131

View full text Add to dashboard Cite

show abstract

“…In most cases, grains' radii in Layer II can achieve 1 -3 cm only a few millimeters from the fault surface, which is the same order of magnitude as grains that are a few centimeters from the fault surface. Consequently, we infer that the cohesiveness of the layer is a result of the ongoing granular deformation, which increases the adhesive forces between comminuted grains as the surface area increases [Gilbert et al, 1991], repacks the rock volume to a denser configuration [Aydin, 1978], and promotes fluid transport into the layer (Figure 5d). The combination of effects lithified the granular material.…”

Section: Cohesive Granular Layer (Ii)mentioning

confidence: 99%

Geometric and rheological asperities in an exposed fault zone

2009

View full text Add to dashboard Cite

Earthquake dynamics are strongly affected by fault zone structure and fault surface geometry. Here we investigate the interplay of bulk deformation and surface topography using detailed structural analysis of a fault zone near Klamath Falls, Oregon, combined with LiDAR measurements of the fault surface. We find that the fault zone has a layered damage architecture. Slip primarily occurs inside a 1–20 mm wide band that contains principal slip surfaces with individual widths of ∼100 μm. The slip band sits atop a cohesive layer which deforms by granular flow. Several fault strands with total slips of 0.5–150 m also have cohesive layers with thicknesses increasing monotonically with slip. The thickness added to the cohesive layer per unit slip decreases with increasing displacement indicating that slip progressively localizes. The main fault is a continuous surface with 10–40 m long quasi‐elliptical geometrical asperities, i.e., bumps. The bumps reflect variations of the thickness of the granular cohesive layer and can be generated by a pinch‐and‐swell instability. As the granular layer is rheological distinct from its surroundings, the asperities are both geometrical and rheological inhomogenities. Modeling slip along wavy faults shows that slip on a surface with a realistic geometry requires internal yielding of the host rock. Our observations suggest that the internal deformation processes in the fault zone include ongoing fracture, slip along secondary faults, and particle rotation. Granular flow is an important part of faulting in this locale. Slip surfaces localize on the border of the granular cohesive layer. The ongoing slip smoothes the surfaces and thus the structural and geometrical evolution of the granular layer creates a preference for continued of slip on the same surface. There is a feedback cycle between slip on the surface and the generation of the granular layer that then deforms and controls the locus of future slip.

show abstract

“…During volcanic eruptions, magma fragmentation can contribute to plume charging near the vent (Gilbert et al 1991;James et al 2008). Charged species are ejected from cracked surfaces following material fracture, and the loss of these charged species results in the formation of charged fragments.…”

Section: Charging and Radioactivity In Volcanic Plumesmentioning

confidence: 99%

Applications of Electrified Dust and Dust Devil Electrodynamics to Martian Atmospheric Electricity

et al. 2016

View full text Add to dashboard Cite

Atmospheric transport and suspension of dust frequently brings electrification, which may be substantial. Electric fields of 10 kV m −1 to 100 kV m −1 have been observed at the surface beneath suspended dust in the terrestrial atmosphere, and some electrification has been observed to persist in dust at levels to 5 km, as well as in volcanic plumes. The interaction between individual particles which causes the electrification is incompletely understood, and multiple processes are thought to be acting. A variation in particle charge with particle size, and the effect of gravitational separation explains to, some extent, the charge structures observed in terrestrial dust storms. More extensive flow-based modelling demonstrates that bulk electric fields in excess of 10 kV m −1 can be obtained rapidly (in less than 10 s) from rotating dust systems (dust devils) and that terrestrial breakdown fields can be obtained. Modelled profiles of electrical conductivity in the Martian atmosphere suggest the possibility of dust electrification, and dust devils have been suggested as a mechanism of charge separation able to maintain current flow between one region of the atmosphere and another, through a global circuit. Fundamental new understanding of Martian atmospheric electricity will result from the ExoMars mission, which carries the DREAMS (Dust characterization, Risk Assessment, and Environment Analyser on the Martian Surface)-B R.G. Harrison

show abstract

Charge measurements on particle fallout from a volcanic plume

Cited by 127 publications

References 17 publications

Volcanic plume electrification: Experimental investigation of a fracture‐charging mechanism

Volcanic plume electrification: Experimental investigation of a fracture‐charging mechanism

Geometric and rheological asperities in an exposed fault zone

Applications of Electrified Dust and Dust Devil Electrodynamics to Martian Atmospheric Electricity

Contact Info

Product

Resources

About