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Oscillatory rheology measurements of particle‐ and bubble‐bearing fluids: Solid‐like behavior of a crystal‐rich basaltic magma
Author(s) -
Namiki Atsuko,
Tanaka Yukie
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 - 10.1002/2017gl074845
Subject(s) - bubble , rheology , viscosity , attenuation , magma , brittleness , basalt , geology , elastic modulus , mineralogy , materials science , mechanics , volcano , composite material , physics , optics , seismology
Abstract The rheology of crystal‐ and bubble‐bearing magmas governs the propagation of seismic waves as well as eruption dynamics. Here “rheology” includes viscous and elastic components and their ratio known as attenuation. We perform an oscillatory rheology measurements, which provide storage (elastic component) and loss (viscous component) moduli, and attenuation, with frequency dependence, using particle‐ and bubble‐bearing fluids whose liquid viscosity is in the range of that of a basaltic melt. We find that both the storage and loss moduli dramatically increase with the particle fraction but weakly depend on the bubble fraction. Solid‐like behavior, equivalent to attenuation < 1, appears in the high particle fraction regime ϕ p >40 vol %. The shallow conduit of Stromboli volcano, filled by a crystal‐rich and low viscosity basaltic magma, may be an example, where shear waves propagate and brittle fractures occur to cause explosive eruptions because of its high crystallinity.