Tectonophysics2022，Vol.82313.DOI:10.1016/j.tecto.2022.229209

Lithospheric flexural isostasy background of the 2017 Ms7.0 Jiuzhaigou earthquake and its implications for material extrusion in the northeastern Bayan Har block

Hao, Hongtao Zhang, Xinlin Wang, Jiapei Wang, Jian Li, Zhongya Hu, Minzhang Wu, Yunlong Zhao, Bin
Tectonophysics2022，Vol.82313.DOI:10.1016/j.tecto.2022.229209
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  • NSTL
  • Elsevier

Lithospheric flexural isostasy background of the 2017 Ms7.0 Jiuzhaigou earthquake and its implications for material extrusion in the northeastern Bayan Har block

Hao, Hongtao 1Zhang, Xinlin 1Wang, Jiapei 1Wang, Jian 1Li, Zhongya 1Hu, Minzhang 1Wu, Yunlong 1Zhao, Bin1
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作者信息

  • 1. China Earthquake Adm
  • 折叠

Abstract

We applied a 2-dimensional, non-spectral technique to investigate the spatial variations of the lithospheric effective elastic thickness (T-e) in the eastern Bayan Har block and its adjacent areas. A program was designed to calculate the Moho flexure induced by topography loading, as well as the Bouguer gravity anomalies caused by that Moho flexure. The T-e values were determined by minimizing the RMS differences between the observed and calculated Bouguer gravity anomalies. The results suggested that T-e varies significantly from eastern Tibet to the Sichuan Basin. The eastern Bayan Har block and northern Sichuan-Yunnan block have low T-e values (0 < T-e < 20 km), indicating an easily deformable lithosphere. The Sichuan Basin has high T-e values (40 km < T-e < 100 km) acts as a rigid block that resists the eastward extrusion of plateau materials. The moderate T-e values (30 km < T-e < 40 km) found under the Longmen Shan fault belt indicate that the lithosphere of the Sichuan Basin plays an important role in supporting the Longmen Shan topography. The extremely low T-e (T-e < 10 km) observed in the seismogenic zone of the Ms7.0 Jiuzhaigou earthquake indicated that the topography is compensated locally, which is significantly different from the Longmen Shan topography. A banded region of relatively low T-e values (< 40 km) stretching from the northeastern Bayan Har block to the southwestern Ordos block sketches out an escape channel for plateau materials, and challenges the existing of crustal flow on the north side of the Sichuan Basin.

Key words

Lithospheric flexural isostasy/Effective elastic thickness/Jiuzhaigou earthquake/Tectonics/EFFECTIVE ELASTIC THICKNESS/LOWER CRUSTAL FLOW/TIBETAN PLATEAU/ELECTRICAL STRUCTURE/EASTERN MARGIN/UPPER-MANTLE/SPATIAL VARIATIONS/KUNLUN FAULT/LONGMEN SHAN/SLIP RATES

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出版年

2022
Tectonophysics

Tectonophysics

EISCI
ISSN：0040-1951
被引量3
参考文献量55
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