Strong S-wave anisotropy in the aftershock region of the 2000 Tottori-ken Seibu, Japan, earthquake (MW6.6)
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- Nakamura Takeshi
- Department of Earth and Planetary Sciences, Kyushu University
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- Takenaka Hiroshi
- Department of Earth and Planetary Sciences, Kyushu University
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- Suzuki Sadaomi
- Department of Earth and Planetary Sciences, Kyushu University
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説明
The 2000 Tottori-ken Seibu earthquake (MW6.6) occurred in Tottori prefecture, western Japan on October 6, 2000. We conducted aftershock observation and analyzed S-wave anisotropy using the aftershocks MJMA2.0 to 3.5 observed at two stations near the aftershock region. The fast S-waves are polarized to almost E-W direction, which corresponds to the P-axis direction of the mainshock. The delay time of the split S-waves ranges between 20 and 100 ms. The crack density inside and outside the aftershock area is estimated from the delay time. The distribution of crack density shows a strong spatial variation and depends on the ratio of the path length inside the aftershock region against the whole path length. Assuming a uniform distribution of anisotropy inside and outside the aftershock region, the crack densities inside and outside are 0.017 and 0.007, respectively. It thus seems probable that in the aftershock region the distribution of cracks is intensive and cracks are opened due to the presence of fluids in seismogenic layers. This considerable spatial variation of anisotropy between inside and outside the aftershock region suggests that the aftershock region may have different mechanical properties from the surrounding area.
収録刊行物
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- Earth, Planets and Space
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Earth, Planets and Space 57 (11), 1055-1062, 2005
地球電磁気・地球惑星圏学会 、公益社団法人 日本地震学会、特定非営利活動法人 日本火山学会、日本測地学会、日本惑星科学会
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詳細情報 詳細情報について
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- CRID
- 1390001206511584896
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- NII論文ID
- 10017470897
- 130003956442
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- NII書誌ID
- AA11211921
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- ISSN
- 18805981
- 13438832
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- NDL書誌ID
- 7737255
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- 本文言語コード
- en
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- データソース種別
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- JaLC
- NDL
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