3-D seismic structure of Kii Peninsula in southwest Japan: Evidence for slab dehydration in the forearc

Mohamed K. Salah, Dapeng Zhao

Research output: Contribution to journalArticlepeer-review

75 Citations (Scopus)

Abstract

Kii Peninsula is located in the forearc region of southwest Japan and has distinct structural and tectonic features characterized by high seismicity in the crust and the subducting Philippine Sea slab, high surface heat flow, high 3He/4He isotopic ratio, and a local change in the geometry of the subducting slab. We have tried to determine detailed 3-D P and S wave velocity structures of this region using a large number of high-quality arrival time data recorded by dense seismic networks on the Japan Islands. From the obtained seismic velocities, we further estimated 3-D distributions of Poisson ratio, crack density, saturation rate and porosity parameter in the study area. Our results show significant heterogeneities in the crust and upper mantle wedge characterized by low seismic velocities, high Poisson ratio, high values of crack density, saturation rate and porosity. These results suggest the existence of fluids in the crust and mantle wedge resulting from the dehydration of the subducting Philippine Sea slab, which can explain the observed geophysical and geochemical features in Kii Peninsula.

Original languageEnglish
Pages (from-to)191-213
Number of pages23
JournalTectonophysics
Volume364
Issue number3-4
DOIs
Publication statusPublished - 2003 Apr 10
Externally publishedYes

Keywords

  • Crack density
  • Kii Peninsula
  • Poisson ratio
  • Porosity parameter
  • Saturation rate
  • Seismic tomography

ASJC Scopus subject areas

  • Geophysics
  • Earth-Surface Processes

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