Mechanism of the Earthquakes with M Equal to or Greater than 6 That Occurred in Volcanoes (Including Calderas) and Their Relation to Volcanic Activity
| Project/Area Number |
60540250
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
固体地球物理学
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| Research Institution | Kyoto University |
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Principal Investigator |
KUBOTERA Akira Faculty of Science Kyoto University, Professor, 理学部, 教授 (70025229)
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| Co-Investigator(Kenkyū-buntansha) |
OIKE Kazuo Disaster Prevention Res. Inst. Kyoto University, Associate Professor, 防災研究所, 助教授 (40027248)
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| Project Period (FY) |
1985 – 1986
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| Project Status |
Completed (Fiscal Year 1986)
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| Budget Amount *help |
¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1986: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1985: ¥1,100,000 (Direct Cost: ¥1,100,000)
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| Keywords | Earthquakes occurred in the volcano / Very-low-frequency earthquake / Swarm earthquake / Shimabara earthquake / 桜島地震 |
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| Research Abstract |
Volcanic earthquakes are defined as those occurring in and around volcanoes. The question if they are related to volcanic activity has long been debated. In order to solve the question, eleven earthquakes with M>=6 that have occurred in volcanoes including calderas in and around Japan since 1904 are investigated. The results are as follows:
1) Two earthquakes of M-7 class have occurred near active volcanoes Sakurajima and Unzen in 1914 and 1922, respectively as opposed to general belief that few larger earthquakes occur near volcanoes;
2) Peculiar earthquakes such as very-low-frequency earthquakes (VL), low-frequeny earthquakes (L), or earthquake swarm (SW) are relatively frequent near volcanoes suggesting a relation to volcanic structures;
3) A large percentage of earthquake-swarm areas are in volcanic areas suggesting that they are failures in inhomogeneous materials of volcanic bodies. However, very few of them unexpectedly were precursors of volcanic eruptions with exceptions at Tokachi-dake in 1962 and at Usu in 1977. No earthquake which was likely generated by magma intrusion has been found; and
4) There are five events of VL in eleven investigated earthquakes. Earthquakes of L or VL type have smaller felt areas than those of normal earthquakes because of their long predominant periods. All of the on-land VL earthquakes had M equal to or greater than 6 and occurred in volcanoes, and may be explained as slow fault slip near volcanic bodies.
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Report
(1 results)
Research Products
(8 results)
