[SCG63-P11] Rheological changes of aphyric basaltic andesite magma based on laboratory experiments of 1986 Izu-Oshima lava
Keywords:Rheology, Magma, Izu-Oshima
The purpose of this study is to unveil nonlinear rheology at unsteady state toward comprehensive modeling of magma rheology. As an initial step, in this presentation, we show our new experimental system and primary results of rheological experiments using volcanic product of lava flowed during 1986 Izu-Oshima fissure eruption B. The experimental system that consists of an electric furnace, a rheometer, and alumina parts, is simplified as much as possible with a view to reducing background noise. By experiments using the Izu-Oshima sample, it was revealed that the relation between the shear stress and the shear rate shows hysteresis and the viscosity depends on the shear rate with decreasing the temperature. We also go a step further and show other characteristics at unsteady state together with microstructures of quenched samples. The results suggest that not only steady state but also unsteady state should be taken into account to capture the entire picture of behavior of magma.