Elastic properties of fault core samples using digital rock physics: Insight into seismogenic fault characterization

Chandoeun Eng, Tatsunori Ikeda, Takeshi Tsuji

    研究成果: 会議への寄与タイプ学会誌査読

    1 被引用数 (Scopus)

    抄録

    To understand characteristics of deep seismogenic faults in the plate convergent margins, we used P- and S-wave velocities (Vp and Vs) of the digital rocks extracted from core samples of ancient plate boundary fault at Nobeoka in Kyushu, southwest Japan. We constructed 3D digital rock models from micro-CT images. The heterogeneous texture, such as cracks and veins were identified based on comparison of the density and porosity from digital rock model with the average of porosity of Nobeoka samples from laboratory measurements. By using Rotated Staggered Grid Finite-Difference Method, we performed dynamic wave propagation simulation and measured the effective Vp, Vs, and ratio of Vp and Vs (Vp/Vs) of 3D digital rock models including cracks and veins. In particular, we investigated the sensitivity of Vp and Vs to crack-filling materials. We replaced the cracks and veins with various elastic materials, such as dry, water, quartz, calcite, and other materials with different bulk and shear modulus. By comparing the elastic properties derived from digital rock with seismic velocity (e.g., Vp/Vs) in the Nankai seismogenic fault, we characterized the deep seismogenic fault. Our results demonstrated that the cracks filled with water significantly decreased seismic velocity and increased Vp/Vs. The Vp/Vs of quartz-filling case was lower than water saturated case. Therefore, high Vp/Vs and low Vp at the transition region from aseismic to seismic regimes in the Nankai Trough are caused by open cracks (or fractures), and low Vp/Vs at coseismic region could be explained by quartz-filling cracks.

    本文言語英語
    出版ステータス出版済み - 2016
    イベント22nd Formation Evaluation Symposium of Japan 2016 - Chiba, 日本
    継続期間: 9月 29 20169月 30 2016

    その他

    その他22nd Formation Evaluation Symposium of Japan 2016
    国/地域日本
    CityChiba
    Period9/29/169/30/16

    !!!All Science Journal Classification (ASJC) codes

    • 地質学
    • エネルギー工学および電力技術
    • 経済地質学
    • 地球化学および岩石学
    • 地盤工学および土木地質学

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