| Budget Amount *help |
¥17,290,000 (Direct Cost: ¥13,300,000、Indirect Cost: ¥3,990,000)
Fiscal Year 2015: ¥2,080,000 (Direct Cost: ¥1,600,000、Indirect Cost: ¥480,000)
Fiscal Year 2014: ¥3,120,000 (Direct Cost: ¥2,400,000、Indirect Cost: ¥720,000)
Fiscal Year 2013: ¥12,090,000 (Direct Cost: ¥9,300,000、Indirect Cost: ¥2,790,000)
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| Outline of Final Research Achievements |
In order to understand the physicochemical conditions of eruption style transition in the shallow conduit, we carried out petrographic study of the products of the 2011 Shinmoedake eruption. The products formed by different explosivity can be distinguished clearly by their mineral assemblage of nanolites, although they have similar microlite characteristics. We further found pyroxene and magnetite crystals smaller than 20-30 nm in width in the lithic fragments: we defined these crystals as ultrananolites.
We also investigated the interfacial tension-driven microstructural relaxation of foamed magma by heating andesitic pumices. Internal pore microstructures of run products relaxed significantly in < 20-30 min at 1000°C through self-contraction to form low connectivity structure. This timescale corresponds to the interval of some active vulcanian explosions. The self-contraction may contribute to accumulate excess gas pressure for vulcanian explosions.
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