Effect of water on seismic attenuation of the upper mantle: The origin of the sharp lithosphere–asthenosphere boundary
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- Chao Liu
- Institute for Planetary Materials, Okayama University, Misasa, Tottori 682-0193, Japan
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- Takashi Yoshino
- Institute for Planetary Materials, Okayama University, Misasa, Tottori 682-0193, Japan
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- Daisuke Yamazaki
- Institute for Planetary Materials, Okayama University, Misasa, Tottori 682-0193, Japan
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- Noriyoshi Tsujino
- Institute for Planetary Materials, Okayama University, Misasa, Tottori 682-0193, Japan
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- Hitoshi Gomi
- Institute for Planetary Materials, Okayama University, Misasa, Tottori 682-0193, Japan
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- Moe Sakurai
- Institute for Planetary Materials, Okayama University, Misasa, Tottori 682-0193, Japan
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- Youyue Zhang
- Institute for Planetary Materials, Okayama University, Misasa, Tottori 682-0193, Japan
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- Ran Wang
- Institute for Planetary Materials, Okayama University, Misasa, Tottori 682-0193, Japan
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- Longli Guan
- Institute for Planetary Materials, Okayama University, Misasa, Tottori 682-0193, Japan
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- Kayan Lau
- Institute for Planetary Materials, Okayama University, Misasa, Tottori 682-0193, Japan
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- Yoshinori Tange
- Japan Synchrotron Radiation Research Institute, Sayo, Hyogo 678-5198, Japan
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- Yuji Higo
- Japan Synchrotron Radiation Research Institute, Sayo, Hyogo 678-5198, Japan
書誌事項
- 公開日
- 2023-07-31
- 資源種別
- journal article
- 権利情報
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- https://creativecommons.org/licenses/by/4.0/
- DOI
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- 10.1073/pnas.2221770120
- 公開者
- Proceedings of the National Academy of Sciences
この論文をさがす
説明
<jats:p>Oceanic lithosphere moves over a mechanically weak layer (asthenosphere) characterized by low seismic velocity and high attenuation. Near mid-ocean ridges, partial melting can produce such conditions because of the high-temperature geotherm. However, seismic observations have also shown a large and sharp velocity reduction under oceanic plates at the lithosphere–asthenosphere boundary (LAB) far from mid-ocean ridges. Here, we report the effect of water on the seismic properties of olivine aggregates in water-undersaturated conditions at 3 GPa and 1,223 to 1,373 K via in-situ X-ray observation using cyclic loading. Our results show that water substantially enhances the energy dispersion and reduces the elastic moduli over a wide range of seismic frequencies (0.5 to 1,000 s). An attenuation peak that appears at higher frequencies (1 to 5 s) becomes more pronounced as the water content increases. If water exists only in the asthenosphere, this is consistent with the observation that the attenuation in the asthenosphere is almost constant over a wide frequency range. These sharp seismic changes at the oceanic LAB far from mid-ocean ridges could be explained by the difference in water content between the lithosphere and asthenosphere.</jats:p>
収録刊行物
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- Proceedings of the National Academy of Sciences
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Proceedings of the National Academy of Sciences 120 (32), 2023-07-31
Proceedings of the National Academy of Sciences