2016 Fiscal Year Final Research Report
Development of monitoring methods for volcanic eruption transition based on analyses of disequilibrium record of erupted materials
| Project/Area Number |
25287141
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Partial Multi-year Fund |
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| Section | 一般 |
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| Research Field |
Petrology/Mineralogy/Economic geology
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| Research Institution | Tohoku University |
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Principal Investigator |
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| Co-Investigator(Kenkyū-buntansha) |
嶋野 岳人 常葉大学, 環境学研究科, 准教授 (70396894)
安井 真也 日本大学, 文理学部, 准教授 (90287566)
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| Project Period (FY) |
2013-04-01 – 2017-03-31
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| Keywords | 火山噴火 / 噴火様式 / 石基 / マイクロライト / ナノライト / 表面張力 / 気泡 / ブルカノ式噴火 |
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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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| Free Research Field |
火山学、岩石学
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