Seismic evidence for a metastable olivine wedge in the subducting Pacific slab under Japan Sea

Guoming Jiang, Dapeng Zhao, Guibin Zhang

Research output: Contribution to journalArticlepeer-review

41 Citations (Scopus)

Abstract

We apply a forward-modeling approach to high-quality arrival time data from 23 deep earthquakes greater than 400 km depth to investigate the detailed structure of the subducting Pacific slab beneath the Japan Sea. Our results show that a finger-like anomaly exists within the subducting Pacific slab below 400 km depth, which has a P-wave velocity 5% lower than the surrounding slab velocity (or 3% lower than that of the normal mantle), suggesting the existence of a metastable olivine wedge (MOW) in the slab. The MOW top and bottom depths are 400 and 560 km, respectively. The MOW is estimated to be about 50 km wide at 400 km depth and close to the slab upper boundary. At 560 km depth the MOW is located at about 25 km below the slab upper boundary. Most of the deep earthquakes are located in the MOW. Our results favor transformational faulting as the mechanism for deep earthquakes.

Original languageEnglish
Pages (from-to)300-307
Number of pages8
JournalEarth and Planetary Science Letters
Volume270
Issue number3-4
DOIs
Publication statusPublished - 2008 Jun 30

Keywords

  • Pacific slab
  • deep earthquakes
  • forward modeling
  • metastable olivine wedge
  • transformational faulting

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science

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