Oscillatory rheology measurements of particle‐ and bubble‐bearing fluids: Solid‐like behavior of a crystal‐rich basaltic magma

Namiki, Atsuko; Tanaka, Yukie

doi:10.1002/2017gl074845

Cited by 18 publications

(18 citation statements)

References 66 publications

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“…We conduct shear deformation experiments by using a rheometer (Anton Paar MCR102). The samples are sandwiched between two parallel plates made of Inconel and placed inside a temperature-controlled oven, the same method used in Gonnermann et al (2017) and Namiki and Tanaka (2017). The maximum temperature achieved by this oven is 1000 °C.…”

Section: Methods Of Shear Deformationmentioning

confidence: 99%

“…f Shows partial fracturing. High-porosity parts denoted by the yellow circles fracture and generate small particles, but other parts shrink by dissipation (Namiki and Tanaka 2017), known as the inverse of the attenuation:…”

Section: Methods Of Shear Deformationmentioning

confidence: 99%

“…Recent seismic observations show the distribution of Q beneath a volcano (Kumagai et al 2014). Gathering Q values under various conditions may help to assess the subsequent eruption styles (Namiki and Tanaka 2017). Fig.…”

Section: Oscillatory Deformation Of Ashmentioning

confidence: 99%

“…The low viscosity of the basaltic andesite ( η m < 10 3 Pa s ) at a high temperature (>1000 °C) may prevent fragmentation. However, the high-porosity magma foam has elastic properties, which allow the fragmentation of low-viscosity magma to generate scoriae (Namiki and Tanaka 2017).…”

Section: Estimated Eruptive Conditionsmentioning

confidence: 99%

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Physical characteristics of scoriae and ash from 2014–2015 eruption of Aso Volcano, Japan

Namiki

Tanaka

Yokoyama

2018

Earth Planets Space

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The activity at Aso Volcano was mainly defined as a sequence of ash emissions and occasional ejections of scoria fragments with ash. Ash emissions sometimes started without notable explosions. The measured porosity of scoriae was as high as 0.94. The scoriae had a flattened shape with a low-porosity outer rim. To elucidate the eruptive conditions causing such ash emission and generation of scoriae, we conducted three series of measurements. First, we heated the high-porosity scoriae from Aso Volcano at 900-1150 °C and found that the heated scoriae shrunk by losing the gas in the bubbles. At the highest temperature, 1150 • C , bubbles segregated from the surrounding melt. Second, we conducted shear deformation experiments of scoriae and ash at 500-950 °C and found that the high-porosity scoriae easily fractured by low normal and shear stresses of ∼ 10 4 Pa at a low temperature of 500 °C. We also found that the fine ash at a high temperature of 950 °C was sintered. Third, we measured the permeability of the sintered ash plate and unheated powder-like ash layer. The permeability of the ash plate is less than 2.5 × 10 −13 m 2 , while that for the ash powder is greater than 10 −11 m 2 . The unheated ash particles could move in the container during the permeability measurements. This effect allowed the formation of pipe-like structures in the ash layer and increased its permeability. On the basis of these measurements, we infer the conditions inside the erupting conduit. There exists high-porosity magma foam in the conduit. The top of the magma foam is cold (<500 °C) and has a sufficiently high porosity (>0.7) to be fractured at a low stress level ( ∼ 10 4 Pa ). The fractured magma foam generates the ash layer above the magma foam. The gas flow from the underlying magma foam makes the high-permeability structure in the ash layer. Eventually, the bottom of the ash layer sinters to regulate the gas flow. The pressurized magma foam breaks the sintered ash layer. The breakage at the bottom of the ash layer may not cause a notable explosion but causes ash emission. The fragmented magma foam becomes high-porosity scoriae at a high temperature, which can generate the low-porosity outer rim by shrinkage and flatted shape. which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.

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Section: Methods Of Shear Deformationmentioning

confidence: 99%

Section: Methods Of Shear Deformationmentioning

confidence: 99%

Section: Oscillatory Deformation Of Ashmentioning

confidence: 99%

Section: Estimated Eruptive Conditionsmentioning

confidence: 99%

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Physical characteristics of scoriae and ash from 2014–2015 eruption of Aso Volcano, Japan

Namiki

Tanaka

Yokoyama

2018

Earth Planets Space

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“…The advanced alteration may cause ductile deformation (Mordensky et al, 2019). A shear wave can propagate in solidifying magmas with high crystallinity at a low velocity of several tens of meters per second (Namiki & Tanaka, 2017). The crack propagation at the shear wave velocity in such a soft rock may excite LP events (Bean et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

A Model Experiment of Fracture Induced Long‐Period Events: Injection of Pressurized Gas Into a Viscoelastic Rock Analog

Namiki

Takahashi

Tsutsui

2019

Geophysical Research Letters

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Low‐frequency events observed in volcanic areas preceding phreatic or phreatomagmatic eruptions may be excited by the injection of pressurized gas into damaged/heated rocks or solidifying magmas. To simulate this process, we conducted a series of gas injection experiments in gels as an analog of such soft rocks. When we inject the pressurized air into a quasi‐Maxwell fluid with higher and lower shear moduli, cracks or a slug appears, respectively. The crack propagation velocity consists of the shear wave velocity of the gel. At the beginning of the crack generation, multiple cracks emerge, causing pulse‐like low‐frequency signals. In contrast, the slug grows faster than the shear wave velocity and excites high‐frequency oscillation. These results show the possibility that the low‐frequency seismicity observed in volcanic regions is the result of not only the resonance of a crack but also the crack propagation in soft rocks.

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Hysteresis of viscosity in a solid-liquid two-phase system with slow slip rate

Muramoto¹,

Ito²

2021

Preprint

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Oscillatory rheology measurements of particle‐ and bubble‐bearing fluids: Solid‐like behavior of a crystal‐rich basaltic magma

Cited by 18 publications

References 66 publications

Physical characteristics of scoriae and ash from 2014–2015 eruption of Aso Volcano, Japan

Physical characteristics of scoriae and ash from 2014–2015 eruption of Aso Volcano, Japan

A Model Experiment of Fracture Induced Long‐Period Events: Injection of Pressurized Gas Into a Viscoelastic Rock Analog

Hysteresis of viscosity in a solid-liquid two-phase system with slow slip rate

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