The Magnetic Fabric of Gouge Mimics the Coseismic Focal Mechanism of the Chi-Chi Earthquake (1999, Mw 7.6)

Yu Min Chou*, Charles Aubourg, En Chao Yeh, Sheng Rong Song, Yi Kai Lin, Fabien Humbert, Xiaodong Jiang, Teh Quei Lee

*此作品的通信作者

研究成果: 雜誌貢獻期刊論文同行評審

摘要

We present a magnetic fabric investigation of small oriented rock fragments from gouges and wall rocks from the Chelungpu fault (Taiwan), where the Chi-Chi earthquake occurred (Mw 7.6, 1999). Samples are obtained from surface outcrops and at a depth of ~1 km, including the 3-mm-thick Chi-Chi principal slip zone. Wall rocks at depth show magnetic foliation roughly parallel to bedding, whereas they are oblique at the surface. Within the gouges, the mean shape of magnetic ellipsoid is oblate, and the degree of anisotropy is up to 12%. The magnetic foliation diverges of ~40° from the fault plane, compatible with a simple shear westward. The magnetic lineation is oblique, resulting probably from coseismic and interseismic records. The reconstructed focal mechanism from the magnetic fabric closely matches the focal mechanism solutions for the Chi-Chi earthquake. Our work demonstrates that magnetic fabric of gouge fragments can bring valuable kinematic information on modern earthquakes.

原文英語
文章編號e2020GL090111
期刊Geophysical Research Letters
47
發行號22
DOIs
出版狀態已發佈 - 2020 十一月 28

ASJC Scopus subject areas

  • 地球物理
  • 地球與行星科學(全部)

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