2014 Fiscal Year Final Research Report
Evolution of pore fluid pressures inferred from earthquake focal mechanisms
| Project/Area Number |
23540493
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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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| Research Field |
Solid earth and planetary physics
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| Research Institution | Nagoya University |
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Principal Investigator |
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| Project Period (FY) |
2011-04-28 – 2015-03-31
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| Keywords | 間隙流体 / 応力 / 地震の発生 / 断層強度 / インバージョン解析 / 注水実験 / モール円 |
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| Outline of Final Research Achievements |
The method of Focal Mechanism Tomography (FMT) is an inversion method to estimate pore fluid pressures from earthquake focal mechanism solutions (Terakawa et al., 2010). We improved the original method so that we can estimate the evolution of pore fluid pressure fields for the purpose of understanding roles of fluid and stress in earthquake generation (Terakawa, 2014). Application of the method to induced seismicity in the Basel enhanced geothermal system in Switzerland shows the evolution of pore fluid pressure in response to fluid injection experiments. The induced events were primarily controlled by a decrease in fault strength due to an increase in pore fluid pressures. However, the largest event (the mainshock) was not directly related to a drastic decrease in fault strength at the hypocenter. The precise relative location of the hypocenters indicated that substantial stress loading by the preshocks on the same fault plane promoted the dynamic rupture of the mainshock.
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| Free Research Field |
地震学
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