Depth variations in seismic velocity in the subducting crust: Evidence for fluid-related embrittlement for intermediate-depth earthquakes

Takahiro Shiina, Junichi Nakajima, Toru Matsuzawa, Genti Toyokuni, Saeko Kita

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

We investigated seismic wave velocity in the subducting crust of the Pacific slab beneath eastern Hokkaido, northern Japan. To detect depth-dependent properties of the seismic velocities in the crust, we analyzed guided waves that propagate in the crust and estimated P wave velocity (Vp) of 6.5–7.5 km/s and S wave velocity (Vs) of 3.6–4.2 km/s at depths of 50–100 km. The results show that the obtained Vp and Vs are 10–15% lower than those expected for the fully hydrated mid-ocean ridge basalt, suggesting the existence of aqueous fluids by ~1 vol % in the crust at this depth range. Our observations suggest that overpressurized fluids channeled in the subducting crust plays as a dominant factor for facilitating the genesis of crustal earthquakes at intermediate depths.

Original languageEnglish
Pages (from-to)810-817
Number of pages8
JournalGeophysical Research Letters
Volume44
Issue number2
DOIs
Publication statusPublished - 2017 Jan 28

Keywords

  • fluid-related embrittelment
  • guided wave
  • intermediate-depth earthquakes
  • oceanic crust
  • seismic velocity
  • subducting zone

ASJC Scopus subject areas

  • Geophysics
  • Earth and Planetary Sciences(all)

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