Seismic evidence for a metastable olivine wedge in the subducting Pacific slab under Japan Sea
Seismic evidence for a metastable olivine wedge in the subducting Pacific slab under Japan Sea
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DOI：
10.1016/j.epsl.2008.03.037
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发表时间：
2008-06
影响因子：
5.3
通讯作者：
G. Jiang;Dapeng Zhao;Guibin Zhang
中科院分区：
文献类型：
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作者：
G. Jiang;Dapeng Zhao;Guibin Zhang
我们应用一种正演模拟方法，从23个深度大于400公里的深地震的高质量的到达时间数据，调查日本海下的俯冲太平洋板块的详细结构。研究结果表明，在400 km深度以下的俯冲板块内存在一个指状异常，其P波速度比周围板块速度低5%（或比正常地幔速度低3%），表明俯冲板块内存在一个亚稳态橄榄石楔（MOW）。MOW顶部和底部深度分别为400和560 km。MOW估计约50公里宽，400公里深，接近板块上边界。在560 km深度处，MOW位于板片上边界以下约25 km处。大部分深源地震发生在MOW地区。我们的研究结果有利于转换断层作为深源地震的机制。
We apply a forward-modeling approach to high-quality arrival time data from 23 deep earthquakes greater than 400 km depth to investigate the detailed structure of the subducting Pacific slab beneath the Japan Sea. Our results show that a finger-like anomaly exists within the subducting Pacific slab below 400 km depth, which has a P-wave velocity 5% lower than the surrounding slab velocity (or 3% lower than that of the normal mantle), suggesting the existence of a metastable olivine wedge (MOW) in the slab. The MOW top and bottom depths are 400 and 560 km, respectively. The MOW is estimated to be about 50 km wide at 400 km depth and close to the slab upper boundary. At 560 km depth the MOW is located at about 25 km below the slab upper boundary. Most of the deep earthquakes are located in the MOW. Our results favor transformational faulting as the mechanism for deep earthquakes.