[SVC43-04] Importance of Q as a measure of the fragmentation potential
Keywords:magma, bubble, rheology
To know the relation between Q and the possibility of fragmentation of a complex fluid, we measured the rheology including Q and strength of high porosity rhyolitic magma at 500–950 degree C (Namiki et al., 2020). The occurrence of brittle fractures is observed in the low-temperature magma (<800 degree C). In this temperature range, the measured Q is high. That is, the elastic energy originated by deformations avoids attenuation and is stored in the bubbly magma until released by fracturing. Our measurements show that Q>1 is a required condition for the fragmentation of complex magma. Our measurements also show that the measured shear modulus and strength are several orders of magnitude lower than bubble-free rhyolite melt, implying that high porosity magma cannot avoid fracturing during magma ascent. Thus, Q can be a measure of the possibility of fragmentation of a complex magma. Knowing the attenuation of the seismic wave is useful to evaluate magma temperature and the possibility of a fragmentation event that may determine subsequent volcanic activities.
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