Seismic anisotropy evidence for dehydration embrittlement triggering intermediate-depth earthquakes.
Seismic anisotropy evidence for dehydration embrittlement triggering intermediate-depth earthquakes.
复制标题
脱水脆化引发中深度地震的地震各向异性证据
DOI：
10.1038/s41598-017-02563-w
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发表时间：
2017-06-01
影响因子：
4.6
通讯作者：
Yao Z
中科院分区：
文献类型：
--
作者：
Wang J;Zhao D;Yao Z
曾有人提出，含水物质的脱水脆化可触发中深地震，并在俯冲板片中形成双地震带。地震各向异性可以提供一个可能的洞察到中深室内地震活动，因为矿物的各向异性特性的变化与水的分布，温度和压力。在这里，我们提出了一个高分辨率模型的P波径向各向异性层析成像的日本俯冲带下降到~400公里的深度，这是使用大量的到达时间数据的本地地震和地震事件。我们的研究结果揭示了中深地震活动的图像和各向异性结构之间的密切相关性。地震活动发生在太平洋和菲律宾海板块的部分，其中正径向各向异性（即，水平速度快于垂直速度）由于脱水而占主导地位，而推断的板块无水部分被发现是无震的，其中负径向各向异性（即，垂直速度比水平速度快）占主导地位。我们的各向异性结果表明，日本的中深地震可能是由俯冲板中含水矿物的脱水脆化引发的。
It has been proposed that dehydration embrittlement of hydrous materials can trigger intermediate-depth earthquakes and form a double seismic zone in a subducting slab. Seismic anisotropy may provide a possible insight into intermediate-depth intraslab seismicity, because anisotropic properties of minerals change with varying water distribution, temperature and pressure. Here we present a high-resolution model of P-wave radial anisotropy tomography of the Japan subduction zone down to ~400 km depth, which is obtained using a large number of arrival-time data of local earthquakes and teleseismic events. Our results reveal a close correlation between the pattern of intermediate-depth seismicity and anisotropic structures. The seismicity occurs in portions of the Pacific and Philippine Sea slabs where positive radial anisotropy (i.e., horizontal velocity being faster than vertical one) dominates due to dehydration, whereas the inferred anhydrous parts of the slabs are found to be aseismic where negative radial anisotropy (i.e., vertical velocity being faster than horizontal one) dominates. Our anisotropic results suggest that intermediate-depth earthquakes in Japan could be triggered by dehydration embrittlement of hydrous minerals in the subducting slabs.