2003 VOL.112 No.6
　表紙写真
日本海溝の沈み込みプレート境界に見られる強い地震波の反射と非アスペリティ

A Strong Seismic Reflection from the Top of the Subduction Oceanic Plate in the Japan Trench and the Possible Non-asperity at the Plate Boundary

　三陸沖の38度30分〜39度30分（口絵2-5図の最も陸よりの測線）にかけての海底地震計とエアガンを組み合わせた人工地震観測の結果を示したもの．最上図は東北大学によって求められた1975年から2002年までのM＞3震源（小さな黒丸）と海底地震計34〜39の位置．下図中，黒の逆三角形は地震計34，35，39の位置．下図はこれら3台の海底地震計で取られた波形を測線の南端からの距離に沿って並べたもの．縦軸は往復走時．図の左は震幅を示すカラーバー．海面下約18kmの深さにあるプレート境界の深さが往復走時で，ほぼ0秒になるように走時の補正（NMO）をしてある．上ほど浅い．0秒付近にある大きな震幅の波群はプレート境界からのPP反射波と解釈される．このような大きなPP反射波を作るには，プレート境界に異常に小さなP波速度を持った物質が有ることが必要であり，そのような物質は密度や摩擦係数も小さく，非地震性のすべりによってプレート沈み込みに伴うひずみを解消しているだろう．すなわち，非アスペリテイとして働く．すなわち，地震波の反射振幅から，三陸沖には非アスペリテイがあることが示唆される．
（写真・説明：笠原順三　Junzo KASAHARA）

CONTENTS 　 Japanese
Special Issue on “Materials Science and Seismological Approaches to Understanding Seismogenic Processes”
     Koichiro FUJIMOTO, Junzo KASAHARA, Koji MASUDA, Toshihiko SHIMAMOTO, Bun'ichiro SHIBAZAKI and Satoshi IDE Introduction to the Special Issue on Materials Science and Seismological Approaches to Understanding Seismogenic Process
811-813
Junzo KASAHARA, Kimihiro MOCHIZUKI, Aya KAMIMURA, Mikako NAKAMURA, Ryota HINO, Tomoaki YAMADA, Toshinori SATO, Peyman P. MOGHADDAM, Minoru NISHINO, Yasuyuki NAKAMURA and Toshihiko KANAZAWA Non-asperities at Subduction Zones and Estimation of Materials at Plate Boundary（Original Article）
814-827
Yuji YAGI and Masayuki KIKUCHI Partitioning between Co-seismic Slip and A-seismic Slip（Review Article）
828-836
Kazushige OBARA Time Sequence of Deep Low-frequency Tremors in the Southwest Japan Subduction Zone: Triggering Phenomena and Periodic Activity（Original Article）
837-849
Eiichi FUKUYAMA Earthquake Dynamic Rupture and Stress Field around the Fault（Original Article）
850-856
Naoyuki KATO Estimation of Frictional Constitutive Parameters on a Plate Boundary: Earthquakes at Asperities off Sanriku, Northeastern Japan（Original Article）
857-868
Teruo YAMASHITA Mechanical Interactions between Fluid Flow and Fault Slip: Effects on the Emergence of Regularity and Complexity in Seismicity （Review Article）
869-884
Arito SAKAGUCHI Observation of the Seismogenic Fault in the Okitsu Melange, Shimanto Accretionary Complex and Stick Slip of Mineral Cementation of Shear Experiment（Original Article）
885-896
Norio SHIGEMATSU, Koichiro FUJIMOTO, Tomoyuki OHTANI, Hidemi TANAKA, Yukari MIYASHITA and Tomoaki TOMITA Structures of Fault Zones in the Brittle-plastic Transition Zone of the Continental Earth's Crust: A Case Study of the Hatagawa Fault Zone（Review Article）
897-914
Takashi ARAI，Hiroaki TSUKAHARA and　Toshiro MORIKIYO Sealing Process with Calcite in the Nojima Active Fault Zone Revealed from Isotope Analysis of Calcite（Original Article）
915-925
Miki TAKAHASHI Continuity and Transport Properties of Shale Smear in Sedimental Basin（Original Article）
926-938
Wataru TANIKAWA, Toshihiko SHIMAMOTO, Wheng-Kuen WEY, Wei-Yu WU, Ching-Weei LIN and When-Chi LAI Permeability Structure and Prediction of the Development of Anomalous Fluid Pressure at Depths in the Focal Area of 1999 Chi-Chi Earthquake（Original Article）
939-952
Koji MASUDA and Takashi ARAI Experimental Study of Fracture and Friction under the Conditions of the Deep Fault Zone: A New Gas-medium, High-pressure and High-temperature Apparatus（Original Article）
953-960
Masao NAKATANI Physicochemical Interpretation of Time-dependent Healing of Frictional Strength: A Quantitative Analysis with Absolute Rate Theory（Original Article）
961-969
Kenji MIBE, Masami KANZAKI, Tatsuhiko KAWAMOTO, Kyoko MATSUKAGE, Yingwei FEI and Shigeaki ONO Investigation of Critical Behavior in Basalt-H2O System Using High-pressure and High-temperature X-ray Radiography（Original Article）
970-978
Toshihiko SHIMAMOTO, Takehiro HIROSE, Kazuo MIZOGUCHI and Hiroyuki NODA High-Velocity Friction of Faults and Earthquake Generating Processes: Current Status and Future Perspectives （Original Article）
979-999
Obituary
  Memorial Address of Dr. Masayuki KIKUCHI （Junzo KASAHARA)
1000
 
Book Reviews
 1001-1007
News
 1008
Proceedings
 1009-1010
Announcement
1011-1012
Pictorials
1 Samples after the Deformation Experiments and Frictional-Slip Experiments under High-Temperature and High-Pressure Conditions （Takashi ARAI, Koji MASUDA and Koichiro FUJIMOTO）  
2 P-wave Velocity Structures of the Izu-Bonin Trench and the Japan Trench Subduction Zones and Mapping of PP Reflection Intensities in the Seismic Zone Over the Japan Trench Forearc Slope （Junzo KASAHARA）  
3 Experimental Simulations of Shale Smear Using Natural Sand-shale Interbedded Specimens （Miki TAKAHASHI）