Simultaneous Analysis of Seismic Velocity and Electrical Conductivity in the Crust and the Uppermost Mantle: A Forward Model and Inversion Test Based on Grid Search

Hikaru Iwamori, Kenta Ueki, Takashi Hoshide, Hiroshi Sakuma, Masahiro Ichiki, Tohru Watanabe, Michihiko Nakamura, Hitomi Nakamura, Tatsuji Nishizawa, Atsushi Nakao, Yasuo Ogawa, Tatsu Kuwatani, Kenji Nagata, Tomomi Okada, Eiichi Takahashi

Research output: Contribution to journalArticlepeer-review

Abstract

This study presents a forward model to quantify the P-wave velocity (VP), S-wave velocity (VS), and electrical conductivity (σ) of the solid-liquid mixtures for a given set of pressure, temperature, lithology, liquid phase (aqueous fluid or melt), liquid fraction, and geometrical parameters in relation to the aspect ratio and connectivity of the liquid phase. This is based on previous experimental and theoretical studies on seismic velocity and electrical conductivity of solid rocks and liquid phases. A total of 78 lithologies, an aqueous fluid with NaCl (∼0–10 wt.%), and mafic to felsic melt appropriate for the crust and the uppermost mantle conditions were described in terms of VP, VS, and σ, as per previous experimental measurements and molecular dynamics simulation. This forward model is provided as a Windows executable program, and generates synthetic VP, VS, and σ, referring to the seismic velocities and electrical conductivity observed in the northeast Japan arc. After generation of the synthetic VP, VS, and σ, the original lithology and liquid parameters (phase, fraction, aspect ratio, and connectivity) were searched by implementing the grid search algorithm to map the misfit over the broad parameter space. The mapping shows the presence of a global misfit minimum around the optimized solution and the possibility of resolving the lithology and the liquid phase parameters based on the observed VP, VS, and σ by using the forward model presented in this study.

Original languageEnglish
Article numbere2021JB022307
JournalJournal of Geophysical Research: Solid Earth
Volume126
Issue number9
DOIs
Publication statusPublished - 2021 Sep

Keywords

  • electrical conductivity
  • forward model
  • grid search algorithm
  • joint inversion
  • seismic velocity
  • solid-liquid mixture

ASJC Scopus subject areas

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

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