Forearc seismogenesis in a weakly coupled subduction zone influenced by slab mantle fluids
Forearc seismogenesis in a weakly coupled subduction zone influenced by slab mantle fluids
复制标题
受板片地幔流体影响的弱耦合俯冲带弧前地震成因
DOI：
10.1038/s41561-023-01260-w
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发表时间：
2023
影响因子：
18.3
通讯作者：
Bécel, Anne
中科院分区：
文献类型：
--
作者：
Cordell, Darcy;Naif, Samer;Evans, Rob;Key, Kerry;Constable, Steven;Shillington, Donna;Bécel, Anne
流体在地震破裂中的作用是了解地震灾害的关键，特别是在俯冲带。阿拉斯加的舒马金裂谷因缺乏大地震成核以及上覆和俯冲板块之间的弱耦合而引人注目。流体已经被用来解释这些观察结果，但是流体的来源仍然不清楚。在这里，我们展示了从Shumagin段收集的海洋大地电磁数据中获得的地下电阻率图像。该模型揭示了板块界面附近约50公里宽的导电（即富流体）带，其流体来源于板块地幔脱水（地壳-地幔边界以下15-25公里）。我们发现，2020年7月的大逆冲地震（在半地段附近成核并向西传播到舒马金段）仅破坏了板块界面的导电部分。这表明，板块地幔流体可以影响发震带，例如，通过形成容易发生动态破裂的斑块。相反，滑移块的上倾同时是电阻性的和弱耦合的，这表明流体本身不是弱耦合的原因，而板块粗糙度起了作用。更广泛地说，这些结果表明，在弧前俯冲带的水收支中，板块地幔流体可能是一个未被重视的流体来源。
The role of fluids in earthquake rupture is key to understanding seismic hazards, particularly at subduction zones. The Shumagin Gap, Alaska, is notable due to a paucity of large earthquake nucleation and weak coupling between the overriding and subducting plates. Fluids have been hypothesized to explain these observations, but the source of the fluids remains unclear. Here we present an image of the subsurface electrical resistivity derived from marine magnetotelluric data collected in the Shumagin segment. The model reveals an approximately 50-km-wide conductive (that is, fluid-rich) zone near the plate interface with fluids sourced from the dehydration of slab mantle (15–25 km beneath the crust–mantle boundary). We find that the July 2020 megathrust earthquake—which nucleated near the Semidi segment and propagated westwards into the Shumagin segment—only ruptured the conductive portion of the plate interface. This suggests that slab mantle fluids can influence the seismogenic zone by, for example, creating patches that are prone to dynamic rupture. In contrast, updip of the slip patch is simultaneously resistive and weakly coupled, suggesting that fluids alone are not responsible for weak coupling and that plate roughness plays a role. More broadly, these results suggest that slab mantle fluids could be an underappreciated fluid source in the water budgets of forearc subduction zones.
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影响因子：
2.5
作者：
Abers, Geoffrey A.;van Keken, Peter E.;Wilson, Cian R.
通讯作者：
Wilson, Cian R.
影响因子：
5.2
作者：
W. Heise;T. Caldwell;E. Bertrand;Graham J. Hill;S. Bennie;Y. Ogawa
通讯作者：
Y. Ogawa
2011年东北冲地震破裂区周围的二维电阻率模型（Mw 9.0）
DOI：
10.1186/s40623-023-01828-1
发表时间：
2023
期刊：
Earth, Planets and Space
影响因子：
--
作者：
H. Ichihara;T. Kasaya;K. Baba;T. Goto;M. Yamano
通讯作者：
M. Yamano
影响因子：
64.8
作者：
Chesley, Christine;Naif, Samer;Bassett, Dan
通讯作者：
Bassett, Dan
影响因子：
3.9
作者：
Guo, Haihao;Keppler, Hans
通讯作者：
Keppler, Hans