Longshot experiments to study velocity anisotropy in the oceanic lithosphere of the northwestern Pacific
書誌事項
- 公開日
- 1983-04
- 権利情報
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- https://www.elsevier.com/tdm/userlicense/1.0/
- DOI
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- 10.1016/0031-9201(83)90094-8
- 公開者
- Elsevier BV
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説明
Abstract Several long-range explosion seismology experiments have been conducted in the northwestern Pacific basin, where one of the oldest oceanic lithospheres is postulated to exist. The experiments were conducted from 1974 to 1980. Highly sensitive ocean-bottom seismographs which had been developed for longshot experiments were used. The lengths of the profiles ranged from 1000 to 1800 km, and the directions were chosen to provide wide azimuthal coverage. One of the aims of this series of experiments was to test the existence of velocity anisotropy on a large, regional scale. The results show that the oceanic lithosphere has anisotropy wherein the velocity changes by 4–7%. The anisotropy extends from a depth of at least 40 to 140 km beneath the sea bottom; however, the magnitude of the anisotropy may vary with depth. The azimuth of the maximum velocity is 150–160° clockwise from north, and coincides with the “fossil” direction of spreading of the Pacific plate, whereas it differs from the present direction of plate motion by ∼ 30°. The azimuth does not seem to depend on depth. In the direction of maximum velocity, the lithosphere is basically two-layered: 8.0–8.2 and 8.6 km s−1. The depth of the interface is 50–60 km beneath the sea floor.
収録刊行物
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- Physics of the Earth and Planetary Interiors
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Physics of the Earth and Planetary Interiors 31 (4), 348-362, 1983-04
Elsevier BV
