Inferring Compressible Fluid Dynamics From Vent Discharges During Volcanic Eruptions

Abstract

Observations at numerous volcanoes reveal that eruptions are often accompanied by continual radio frequency (CRF) emissions. The source of this radiation, however, has remained elusive until now. Through experiments and the analysis of field data, we show that CRF originates from proximal discharges driven by the compressible fluid dynamics associated with individual volcanic explosions. Blasts produce flows that expand supersonically, generating regions of weakened dielectric strength in close proximity to the vent. As erupted material—charged through fragmentation, friction, or other electrification process—transits through such a region, pyroclasts remove charge from their surfaces in the form of small interparticle spark discharges or corona discharge. Discharge is maintained as long as overpressured conditions at the vent remain. Beyond describing the mechanism underlying CRF, we demonstrate that the magnitude of the overpressure at the vent as well as the structure of the supersonic jet can be inferred in real time by detecting and locating CRF sources.

The Effect of Electrostatic Charge on the Propagation of GPS (L‐band) Signals Through Volcanic Plumes

“…Instruments like the Lightning Mapping Array (LMA) can provide extremely accurate four‐dimensional maps of discharges in plumes. Processed LMA data have been used to show that charging and discharge processes reflect the kinematics of the associated volcanic atmospheric flow and can be used to obtain information that would otherwise be opaque to observation (Aizawa et al, ; Behnke et al, ; Behnke & Eric, ; Cimarelli et al, ; Méndez Harper et al, ; Thomas et al, ).…”

Origin of large-amplitude oscillations of dust particles in a plasma sheath

“…Dusty or complex plasmas, consisting of microscopic particles immersed in a weakly ionized gas, are ubiquitous in the natural universe and play important roles in man-made systems [1][2][3][4][5][6]. When exposed to a plasma environment, particles gain charge by collecting discrete ions and electrons on their surfaces.…”

Impulsive Volcanic Plumes Generate Volcanic Lightning and Vent Discharges: A Statistical Analysis of Sakurajima Volcano in 2015

“…Mareev and Dementyeva (2017) show that relative velocities and turbulence are key factors in noninductive and triboelectric charging. Additionally, rapidly expanding jets are more likely to generate shock waves, which have been shown by Méndez Harper et al (2018) to enhance the conditions for electrical breakdown at the vent. The model results also imply that the production of volcanic electrical activity is related to the flux of material at the vent.…”