2010 Fiscal Year Final Research Report
Source image of low-frequency events in Nankai trough
| Project/Area Number |
20740262
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| Research Category |
Grant-in-Aid for Young Scientists (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Solid earth and planetary physics
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| Research Institution | Japan Agency for Marine-Earth Science and Technology |
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Principal Investigator |
OBANA Koichiro Japan Agency for Marine-Earth Science and Technology, 地球内部ダイナミクス領域, 研究員 (10359200)
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| Project Period (FY) |
2008 – 2010
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| Keywords | 南海トラフ / 低周波微動 / 海底地震計 |
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| Research Abstract |
Anomalous very-low-frequency (VLF) earthquakes have been observed near the trough axis along the Nankai trough by land seismic networks. The VLF earthquakes were characterized by a dominant frequency of about 10 s and a lack of energy at higher frequencies. This study shows that VLF earthquakes and low frequency tremors occurred near the toe of the accretionary prism based on close range observations using ocean bottom seismographs deployed in the source area. The VLF earthquakes have a focal mechanism of a low-angle reverse fault. The low-frequency events likely relate to an activity of reverse fault in a shallow accretionary prism.
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