Geodynamic subduction models constrained by deep earthquakes beneath the Japan Sea and eastern China

Abstract Details of Pacific plate subduction under the Japan Sea and associated current seismicity remain challenging. Seismic tomography reveals a continuous slab dipping at ~30° down to ~600 km, and earthquake mechanisms point to down-dip compression. Further, the slab is lying at the 660-km disco...

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Autores principales:	Hana Čížková, Jiří Zahradník, Junqing Liu, Craig R. Bina
Formato:	article
Lenguaje:	EN
Publicado:	Nature Portfolio 2020
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/f9120078c2dd4de5b63d95dcee8c176d
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spelling	oai:doaj.org-article:f9120078c2dd4de5b63d95dcee8c176d2021-12-02T17:04:08ZGeodynamic subduction models constrained by deep earthquakes beneath the Japan Sea and eastern China10.1038/s41598-020-62238-x2045-2322https://doaj.org/article/f9120078c2dd4de5b63d95dcee8c176d2020-03-01T00:00:00Zhttps://doi.org/10.1038/s41598-020-62238-xhttps://doaj.org/toc/2045-2322Abstract Details of Pacific plate subduction under the Japan Sea and associated current seismicity remain challenging. Seismic tomography reveals a continuous slab dipping at ~30° down to ~600 km, and earthquake mechanisms point to down-dip compression. Further, the slab is lying at the 660-km discontinuity, and this zone is aseismic. We suggest that this pattern results from the slab’s negative thermal buoyancy, resistance of the viscous lower mantle, and buoyancy forces associated with the phase transitions at 410 km and 660 km. Our model comprises an ageing subducting plate, nonlinear rheology and major phase transitions. The model explains the observed low dip angle of the slab and predicts a detailed stress pattern related to bending down to 450 km, followed by unbending as the slab is laid flat upon the 660 km boundary. Remarkably, in the bending/unbending regions, down-dip compression occurs close to the slab top/bottom, respectively. As only down-dip compression is observed, we argue that the earthquakes are mapping the top and bottom of the slab. The absence of seismicity in the flat-lying slab is explained by significantly lower stresses and higher temperatures. With this new knowledge, increasingly accurate seismic locations will considerably improve images of finite-extent slab geometry.Hana ČížkováJiří ZahradníkJunqing LiuCraig R. BinaNature PortfolioarticleMedicineRScienceQENScientific Reports, Vol 10, Iss 1, Pp 1-10 (2020)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Hana Čížková Jiří Zahradník Junqing Liu Craig R. Bina Geodynamic subduction models constrained by deep earthquakes beneath the Japan Sea and eastern China
description	Abstract Details of Pacific plate subduction under the Japan Sea and associated current seismicity remain challenging. Seismic tomography reveals a continuous slab dipping at ~30° down to ~600 km, and earthquake mechanisms point to down-dip compression. Further, the slab is lying at the 660-km discontinuity, and this zone is aseismic. We suggest that this pattern results from the slab’s negative thermal buoyancy, resistance of the viscous lower mantle, and buoyancy forces associated with the phase transitions at 410 km and 660 km. Our model comprises an ageing subducting plate, nonlinear rheology and major phase transitions. The model explains the observed low dip angle of the slab and predicts a detailed stress pattern related to bending down to 450 km, followed by unbending as the slab is laid flat upon the 660 km boundary. Remarkably, in the bending/unbending regions, down-dip compression occurs close to the slab top/bottom, respectively. As only down-dip compression is observed, we argue that the earthquakes are mapping the top and bottom of the slab. The absence of seismicity in the flat-lying slab is explained by significantly lower stresses and higher temperatures. With this new knowledge, increasingly accurate seismic locations will considerably improve images of finite-extent slab geometry.
format	article
author	Hana Čížková Jiří Zahradník Junqing Liu Craig R. Bina
author_facet	Hana Čížková Jiří Zahradník Junqing Liu Craig R. Bina
author_sort	Hana Čížková
title	Geodynamic subduction models constrained by deep earthquakes beneath the Japan Sea and eastern China
title_short	Geodynamic subduction models constrained by deep earthquakes beneath the Japan Sea and eastern China
title_full	Geodynamic subduction models constrained by deep earthquakes beneath the Japan Sea and eastern China
title_fullStr	Geodynamic subduction models constrained by deep earthquakes beneath the Japan Sea and eastern China
title_full_unstemmed	Geodynamic subduction models constrained by deep earthquakes beneath the Japan Sea and eastern China
title_sort	geodynamic subduction models constrained by deep earthquakes beneath the japan sea and eastern china
publisher	Nature Portfolio
publishDate	2020
url	https://doaj.org/article/f9120078c2dd4de5b63d95dcee8c176d
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Geodynamic subduction models constrained by deep earthquakes beneath the Japan Sea and eastern China

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