2022 Fiscal Year Final Research Report
An attempt to establish a method for estimating the magma intrusion volume and the timing of eruption from volcano tectonic earthquakes
| Project/Area Number |
18K03781
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Review Section |
Basic Section 17040:Solid earth sciences-related
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| Research Institution | Kyoto University |
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Principal Investigator |
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| Project Period (FY) |
2018-04-01 – 2023-03-31
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| Keywords | 火山構造性地震 / 群発地震 / 地震エネルギー / 噴火時刻 / 地殻変動 / 体積変化量 / 応力場 / 噴出量 |
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| Outline of Final Research Achievements |
Volcano tectonic earthquakes originate from brittle fracture caused by stress changes in surrounding rocks due to magma intrusion. Magma intrusion causes not only a swam of volcano tectonic earthquakes and but also significant crustal deformation. An empirical equation is derived for the volume change of the deformation sources and seismic moment (energy) of volcano tectonic earthquakes. Using this empirical formula, we can estimate the volume of magma intrusion from observations of volcano tectonic earthquakes. The growth of a dike, a form of magma intrusion, increases the stress in the surrounding rocks, and the stress exceeds the fracture strength, which explains the occurrence process of volcano tectonic earthquakes. It is also revealed that a cluster of volcano tectonic earthquakes progressed from shallow to deep depths with the growth of the dike.
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| Free Research Field |
地球物理学
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| Academic Significance and Societal Importance of the Research Achievements |
貫入したマグマの全てが噴火によって放出されるわけではないが，貫入マグマの量は放出しうるマグマ量の上限を規定する。噴火による放出量は災害の規模に関わるため，放出量の上限を事前に想定する意義がある。そのため，貫入マグマ量を推定することは重要であるが，地殻変動観測が不十分な発展途上国の火山であっても最低限は地震観測が行われているため，本研究成果の地震からのマグマ貫入量の推定手法の構築は意義がある。
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