Teleseismic shear wave tomography of the Japan subduction zone

Koichi Asamori, Dapeng Zhao

Research output: Contribution to journalArticlepeer-review

22 Citations (Scopus)

Abstract

We present a high-resolution shear wave tomography of the Japan subduction zone down to a depth of 700 km, which is determined by inverting a large number of high-quality S-wave arrival-time data from local earthquakes and teleseismic events. The subducting Pacific and Philippine Sea (PHS) slabs are revealed clearly as high-velocity (high-V) zones, whereas lowvelocity (low-V) anomalies are revealed in themantle wedge above the two slabs. The PHS slab has subducted aseismically down to a depth of 480 km under the Japan Sea and to a depth of 540 km under the Tsushima Strait. A window is revealed within the aseismic PHS slab, being consistent with P-wave tomography. Prominent low-V and high-Poisson's ratio (σ) anomalies exist below the PHS slab and above the Pacific slab, which reflect hot and wet mantle upwelling caused by the joint effect of deep dehydration of the Pacific slab and convective circulation process in the mantle wedge above the Pacific slab. The hot and wet mantle upwelling has caused the complex geometry and structure of the PHS slab in SW Japan, and contributed to the Quaternary volcanism along the Japan Sea coast. In eastern Japan, low-V zones are revealed at depths of 200-700 km below the Pacific slab, which may reflect hot upwelling from the lower mantle or even the core-mantle boundary.

Original languageEnglish
Pages (from-to)1752-1772
Number of pages21
JournalGeophysical Journal International
Volume203
Issue number3
DOIs
Publication statusPublished - 2015

Keywords

  • Dynamics of lithosphere and mantle
  • Dynamics: convection currents, and mantle plumes
  • Mantle processes
  • Seismic tomography
  • Subduction zone processes
  • Volcanic arc processes

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology

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