2021 Fiscal Year Final Research Report
Study on the relationship between pyroclastic eruption sequence and magma geochemistry to contribute to the countermeasure at large-scale eruption
Project/Area Number |
19K03999
|
Research Category |
Grant-in-Aid for Scientific Research (C)
|
Allocation Type | Multi-year Fund |
Section | 一般 |
Review Section |
Basic Section 17030:Human geosciences-related
|
Research Institution | Osaka Prefecture University |
Principal Investigator |
Miura Daisuke 大阪府立大学, 理学(系)研究科(研究院), 教授 (50371414)
|
Project Period (FY) |
2019-04-01 – 2022-03-31
|
Keywords | クッタラ / 巨大噴火 / マグマ |
Outline of Final Research Achievements |
An informative estimate on "duration in volcanic ash fall" is critically important measure to mitigate volcanic hazard at inhabited areas and that to reduce the hazard posed by a large-scale pyroclastic eruption. There are, however, few instrumental observation records and historical documents, because such a large-scale eruption is rare to occur. The stability of eruption column is crucial to maintain ash fall for "a certain duration" in distal areas. An unstable column may result in the column collapse that drives a shorter duration in ash fall and that deposits a pyroclastic flow. In this study, we conducted a geological survey and rock chemistry analysis for explosive pyroclastic ejecta to explore the reason why the eruption column may be transferred from stable to unstable. Consequently, we have confirmed that an irreversible column collapse was attributed to the caldera formation, of which was induced by the silicic magma with high temperature and low pressure.
|
Free Research Field |
自然災害科学
|
Academic Significance and Societal Importance of the Research Achievements |
火山の巨大噴火が,社会にもたらす災厄について熟考すると,降下火山灰が最も大きなインパクトを与え,防災対策において最優先の課題である.しかし,巨大噴火は滅多に起こらないため,機器観測や有史記録が少なく,対策立案の示標となる降下火山灰の継続時間を得るのが困難である.そこで本研究では,過去の火山噴出物を調べ,降下火山灰の継続時間が変化する原因を検討した.具体的には,巨大噴火の様式推移とマグマの化学的性質を調べ,マグマの性質に起因する噴火の推移(変化)が継続時間に影響することが判った.本研究のようなアプローチは,過去の噴出物を研究対象とすることから,世界中の巨大噴火において同様の検討が可能である.
|