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A viscous‐to‐brittle transition in eruptions through clay suspensions
Author(s) -
Schmid Diana,
Scheu Bettina,
Wadsworth Fabian B.,
Kennedy Ben M.,
Jolly Arthur,
Dingwell Donald B.
Publication year - 2017
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2017gl073641
Subject(s) - ejecta , volcano , geology , rheology , petrology , magma , jet (fluid) , geothermal gradient , geophysics , geochemistry , mineralogy , mechanics , physics , thermodynamics , quantum mechanics , supernova
Volcanic lakes are often associated with active geothermal circulation, mineral alteration, and precipitation, each of which can complicate the analysis of shallow magma physics, geophysical signals, and chemical signals. The rheology of the lake and associated hydrothermal system affects the eruptive activity as bubbles ascend and burst through the lake producing distinct ejection behavior. We investigate such phenomena by conducting scaled experiments in which heated water‐clay suspensions are decompressed rapidly from relevant pressures. After a jet phase of expanding vapor, the suspensions break up into ejecta that are either angular or droplet geometry. We parameterize these regimes and find a universal clay volume fraction of 0.28 below which the ejecta are form droplets and above which the ejecta are angular. We propose a regime diagram for optical observations of active lakes, which allows rheological characterization and informs volcanic monitoring.