日本地球惑星科学連合2015年大会

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口頭発表

セッション記号 S (固体地球科学) » S-CG 固体地球科学複合領域・一般

[S-CG57] 変動帯の構造・進化とダイナミクス

2015年5月27日(水) 14:15 〜 16:00 A06 (アパホテル&リゾート 東京ベイ幕張)

コンビーナ:*竹下 徹(北海道大学大学院理学院自然史科学専攻)、佐藤 比呂志(東京大学地震研究所地震予知研究センター)、尾鼻 浩一郎(海洋研究開発機構 地震津波海域観測研究開発センター)、西村 卓也(京都大学防災研究所)、深畑 幸俊(京都大学防災研究所)、加藤 愛太郎(名古屋大学大学院環境学研究科)、武藤 潤(東北大学大学院理学研究科地学専攻)、佐藤 活志(京都大学大学院理学研究科地球惑星科学専攻)、小平 秀一(海洋研究開発機構 地球内部ダイナミクス領域)、鷺谷 威(名古屋大学減災連携研究センター)、石山 達也(東京大学地震研究所)、松原 誠(防災科学技術研究所)、池田 安隆(東京大学大学院理学系研究科地球惑星科学専攻)、座長:蔵下 英司(東京大学地震研究所)

15:57 〜 16:00

[SCG57-P16] 一軸圧縮に伴う含水花崗岩の弾性波速度と電気伝導度の変化

ポスター講演3分口頭発表枠

*森本 美咲1渡辺 了1 (1.富山大学地球科学教室)

キーワード:地震波速度, 電気伝導度, 異方性, 流体, 圧縮, 応力

Geophysical observations have shown that fluids exist pervasively within the crust. Fluids are mainly situated at intra-grain cracks and open grain boundaries. Since the opening of cracks strongly depends on the stress state, bulk properties such as seismic velocity and electrical conductivity, which are strongly affected by fluid-filled cracks, should be anisotropic under a stress state. In order to understand the anisotropy in velocity and conductivity under stress, we have been constructing an experimental system for studying the anisotropy in elastic wave velocity and electrical conductivity in a brine-saturated granitic rock under uni-axial stress.
The loading system is composed of a hand press (Maximum load: 20 kN), a load cell and stainless steel end-pieces, which contains ultrasonic transducers for velocity measurements in the axial direction. A fine grained (100-500 ?m) biotite granite (Aji, Kagawa Pref., Japan) was selected as a rock sample for its small grain size and textural uniformity. A cylindrical sample (D=26 mm, L=30 mm), to the cylindrical surface of which ultrasonic transducers are mounted for velocity measurements in the radial direction, is assembled with end-pieces, and then loaded. One compressional wave velocity and two shear wave velocities can be measured in the axial and two radial directions. Electrical impedance can also be measured in the axial and radial directions.
Preliminary runs on a dry rock sample have showed that velocities in the axial direction increased significantly with the axial compression. No significant change was observed in velocities propagating in the radial directions. These observations can be explained by the closure of cracks perpendicular or subperpendicular to the compression axis. Experiments on wet samples will also be reported in this poster.