Seismic anisotropy of the upper crust in the mountain ranges of Taiwan from the TAIGER explosion experiment

Hao Kuo-Chen, Piotr Środa, Francis Wu, Chien Ying Wang, Yao Wen Kuo

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

Abstract

Taiwan is known as a strongly anisotropic region observed from SKS 1 - 2 s delay time and other teleseismic phases. An estimate of the crustal contribution to the total anisotropy from the foliated Central Range is essential to understanding the overall teleseismic results. We used P wave arrivals from the dense seismic arrays deployed during the TAIGER active source experiments and the permanent broadband seismic stations to determine the crustal anisotropy. From the arrival time analysis as a function of azimuth, we detected a clear cos(2θ) pattern. The strength of the crustal anisotropy (0 - 15 km depth) reaches 8 - 10% and the fast direction azimuth is around 35 - 43° for the overall mountain ranges. The anisotropic variations from the central to the north are found in detail. The results could indicate that the upper crustal delay time contribution of teleseismic shear waves reaches up to 0.45 s. The geological data at the surface and geophysical observations imply a coherent deformation from the surface to the lower crust or even down to the upper mantle.

Original languageEnglish
Pages (from-to)963-970
Number of pages8
JournalTerrestrial, Atmospheric and Oceanic Sciences
Volume24
Issue number6
DOIs
StatePublished - Dec 2013

Keywords

  • Foliation
  • Seismic anisotropy
  • Taiwan orogeny

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