Inferring Compressible Fluid Dynamics From Vent Discharges During Volcanic Eruptions
| Autor: | Josef Dufek, R. J. Thomas, Damien Gaudin, J. S. Méndez Harper, Corrado Cimarelli |
|---|---|
| Rok vydání: | 2018 |
| Předmět: |
geography
geography.geographical_feature_category 010504 meteorology & atmospheric sciences Compressible fluid dynamics Pyroclastic rock Geophysics 010502 geochemistry & geophysics 01 natural sciences Overpressure Volcano General Earth and Planetary Sciences Supersonic speed Dirty thunderstorm Choked flow Geology Corona discharge 0105 earth and related environmental sciences |
| Zdroj: | Geophysical Research Letters |
| ISSN: | 1944-8007 0094-8276 |
| DOI: | 10.1029/2018gl078286 |
| Popis: | 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 materialcharged through fragmentation, friction, or other electrification processtransits 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. |
| Databáze: | OpenAIRE |
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