Thrust-type focal mechanisms of tectonic tremors in Taiwan: Evidence of subduction

Satoshi Ide*, Suguru Yabe, Hsin Ju Tai, Kate Huihsuan Chen

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

21 Citations (Scopus)


Unlike tectonic tremors in subduction zones and along transform faults, the hosting structure for tremors in Taiwan remains debated. Tectonic tremors in Taiwan have been discovered at ∼30km depth beneath the southern Central Range, which is a young and active collisional mountain belt. Here we provide the first evidence for the focal mechanism of tremor using moment tensor inversion in the very low frequency band, employing broadband seismograms stacked relative to the hypocentral time of tremor. The best solution corresponds to low-angle thrust faulting, suggesting the subduction of the Eurasian plate. This mechanism is consistent with strong tidal modulation of tremor activity but differs from the normal-type faulting that dominates regional shallow earthquakes. This result suggests vertical variations in the tectonic stress regime. Thrust faulting may be facilitated by a decrease in normal stress due to the buoyant roots of the mountain belt and local high fluid pressure.

Original languageEnglish
Pages (from-to)3248-3256
Number of pages9
JournalGeophysical Research Letters
Issue number9
Publication statusPublished - 2015 May 16


  • Taiwan
  • focal mechanism
  • subduction
  • tectonic tremor
  • very low frequency earthquake

ASJC Scopus subject areas

  • Geophysics
  • General Earth and Planetary Sciences


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