Postseismic geodetic signature of cold forearc mantle in subduction zones
Postseismic geodetic signature of cold forearc mantle in subduction zones
复制标题
俯冲带冷前弧地幔的震后大地测量特征
DOI：
10.1038/s41561-020-00679-9
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发表时间：
2021
影响因子：
18.3
通讯作者：
Kelin Wang
中科院分区：
文献类型：
--
作者：
Haipeng Luo;Kelin Wang
冷的前弧与热弧和后弧之间的强烈热对比被认为是各种俯冲带过程的基础。然而，这种对比的直接观测证据相当有限。如果这种对比是存在的，它必然会在地幔楔中造成流变对比：在地震周期的时间尺度上，弧前是弹性的，弧后是粘弹性的。在这里，我们证明了大俯冲地震后的震后变形为热控流变对比提供了独立的证据。具体地说，我们表明，向海的震后运动在冷的前弧地幔楔边缘被向上偏转，导致了火山弧向海的诊断性隆起。通过对2011年9级东北大地震、2010年8.8级Maule地震、2007年8.4级Bengkulu地震和1960年9.5级智利地震后形变的数值模拟，以及全球地震后隆起测量结果的综合分析，我们发现，无论构造环境的多样性如何，弧前地幔都是冷的。我们的发现还表明，1960年智利地震发生8年后的实地调查提供了一些最早的地震后粘弹性变形的证据。我们认为，建立长期热过程和短期地震周期变形之间的联系对于理解俯冲带动力学是重要的。根据数值模拟和俯冲带震后隆升资料的综合分析，大俯冲地震后的变形反映了地幔楔体及其鼻部之间的热对比。
A sharp thermal contrast between the cold forearc and the hot arc and backarc is considered fundamental to various subduction-zone processes. However, direct observational evidence for this contrast is rather limited. If this contrast is present, it must cause a rheological contrast in the mantle wedge: elastic in the forearc and viscoelastic in the arc and backarc for the timescale of earthquake cycles. Here we demonstrate that postseismic deformation following large subduction earthquakes provides independent evidence for the thermally controlled rheological contrast. Specifically, we show that seaward postseismic motion is deflected upward at the edge of the cold forearc mantle wedge, causing diagnostic uplift just seaward of the volcanic arc. From numerical simulations of postseismic deformation following the 2011 moment magnitude ( M w ) 9 Tohoku-oki, 2010 M w 8.8 Maule, 2007 M w 8.4 Bengkulu and 1960 M w 9.5 Chile earthquakes, together with a global synthesis of postseismic uplift measurements, we find that cold forearc mantle is present irrespective of the diversity in tectonic settings. Our findings also indicate that field surveys eight years after the 1960 Chile earthquake provided some of the earliest evidence for viscoelastic postseismic deformation. We suggest that the established link between long-term thermal processes and short-term earthquake cycle deformation is important to understanding subduction-zone dynamics. Deformation after large subduction earthquakes reflects the thermal contrast between the mantle wedge and its nose, according to numerical simulations and a synthesis of postseismic uplift data from subduction zones.
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影响因子：
3.7
作者：
Shaoyang Li;J. Bedford;M. Moreno;W. Barnhart;M. Rosenau;O. Oncken
通讯作者：
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影响因子：
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作者：
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通讯作者：
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