2009 VOL.118 No.1  
　表紙写真
Methane Hydrate Block Exposed on the Sea-floor of the Umitaka Spur, Joetsu Basin

　Large mass of methane hydrate exposed on the seafloor, photographed by the Super-Harp ultra high-resolution, high-sensitivevideo-camera of the ROV Hyper-Dolphin of JAMSTEC.The width of the manipulator is approximately 18 cm. Collapse structure zone on the Umitaka spur.Water depth is 900 m.White materials at the wall upper-left portion of the wall are also methane hydrate.Methane hydrate exposed to sea water is expected to be dissolved as the seawater is under-saturated with methane.The large hydrate block in the photo is surrounded by a sharp and broken surface.The exposed methane hydrate block is considered to be a broken remnant of a large mass that collapsed and floated up to the sea-surface due to gravity imbalance and gas pressure below the hydrate.
(Ryo MATSUMOTO; photo: courtesy of JAMSTEC (Natsushima NT07-20))
　  
CONTENTS Japanese
　Special Issue on “Methane Hydrate (Part I): Occurrence, Origin, and Environmental Impact”
  Ryo MATSUMOTO, Sadao NAGAKUBO, Yoshihisa OKUDA, Manabu TANAHASHI, Yasuyuki MURAMATSU, Hitoshi SHOJI, Shiro HASEGAWA, Tomio INAZAKI and Junzo KASAHARA Preface for the Special Issue on “Methane Hydrate (Part I): Occurrence, Origin, and Environmental Impact”
1-6
  Ryo MATSUMOTO Overview of Gas Hydrate:
Impact of the Discovery of a Large Ice-like Carbon Reservoir under the Seafloor (Review Article)
7-42
  Ryo MATSUMOTO, Yoshihisa OKUDA, Akihiro HIRUTA, Hitoshi TOMARU, Eiichi TAKEUCHI, Risa SANNO, Maki SUZUKI, Kazuhiro TSUCHINAGA, Yasushi ISHIDA, Osamu ISHIZAKI, Rika TAKEUCHI, Junko KOMATSUBARA, Antonio Fernando FREIRE, Hideaki MACHIYAMA, Chiharu AOYAMA, Masato JOSHIMA, Mineo HIROMATSU, Glen SNYDER, Hideki NUMANAMI, Mikio SATOH, Yasumochi MATOBA, Hiroshi NAKAGAWA, Yoshitaka KAKUWA, Shigenori OGIHARA, Katsunori YANAGAWA, Michinari SUNAMURA, Tadanori GOTO, Hailong LU and Takeshi KOBAYASHI Formation and Collapse of Gas Hydrate Deposits in High Methane Flux Area of the Joetsu Basin, Eastern Margin of Japan Sea (Original Article)
43-71
  Masato JOSHIMA, Kiyokazu NISHIMURA, Kiyoyuki KISIMOTO, Mineo HIROMATSU, Mikio SATO and Ryo MATSUMOTO Micro-topography and Shallow Sub-bottom Structure on the Gas Hydrate Area off Joetsu City, Niigata, Japan: DAI-PACK Mapping Study (Original Article)
72-92
  Tatsuo SAEKI, Takao INAMORI, Sadao NAGAKUBO, Peter WARD and Eiichi ASAKAWA 3D Seismic Velocity Structure below Mounds and Pockmarks in the Deep Water Southwest of the Sado Island (Original Article)
93-110
  Hitoshi TOMARU, Hirotsugu MINAMI, Hitoshi SHOJI, Akihiro HIRUTA, Ryo MATSUMOTO, Zunli LU, Udo FEHN, Young K. JIN and Anatoly OBZHIROV Geochemistry of Halogen and Iodine Radioisotope (129I) in Pore Waters from Shallow Gas Hydrate Systems in the Okhotsk Sea and Japan Sea (Original Article)
111-127
  Shigenori OGIHARA, Osamu ISHIZAKI and Ryo MATSUMOTO Organic Geochemical Analysis of Push Core Sediment Samples Collected from NT-06-19 (Umitaka Spur and Joetsu Knoll off Naoetsu) (Original Article)
128-135
  Yasumochi MATOBA and Hiroshi NAKAGAWA Distribution of Recent Benthic Foraminifera in the Methane Seepage Area off Joetsu in the Eastern Japan Sea (Original Article)
136-155
  Chiharu AOYAMA and Ryo MATSUMOTO Acoustic Surveys of Methane Plumes by Quantitative Echo Sounder in Japan Sea and the Estimate of the Seeping Amount of the Methane Hydrate Bubbles (Original Article)
156-174
  Hitoshi SHOJI, Young K. JIN, Anatoly OBZHIROV, Alexander SALOMATIN, Boris BARANOV, Vyacheslav GLADYSH, Akihiro HACHIKUBO, Hirotsugu MINAMI, Satoshi YAMASHITA and Nobuo TAKAHASHI Methane Hydrates and Plumes in the Sea of Okhotsk (Original Article)
175-193
  Hirotsugu MINAMI, Alexey KRYLOV, Hirotoshi SAKAGAMI, Akihiro HACHIKUBO, Kinji HYAKUTAKE, Hitoshi TOMARU, Masato KIDA, Nobuo TAKAHASHI, Hitoshi SHOJI, Tatiana MATVEEVA, Young K. JIN, Anatoly OBZHIROV and Jeffrey POORT Geochemistry of Pore Waters from Gas Hydrate-bearing Sediment Cores Retrieved at the Sea of Okhotsk (Original Article)
194-206
  Akihiro HACHIKUBO, Hirotoshi SAKAGAMI, Hirotsugu MINAMI, Yutaka NUNOKAWA, Hitoshi SHOJI, Tatiana MATVEEVA, Young K. JIN and Anatoly OBZHIROV Isotopic Composition and Crystallographic Properties of Gas Hydrate in the Sea of Okhotsk (Original Article)
207-221
 
Book Reviews
222-226
Proceedings
227-228
Announcement
229-231
　Pictorial
  1: Recovery of Methane Hydrate from the Sea Floor (Ryo MATSUMOTO, Yoshihisa OKUDA and Hitoshi TOMARU)
i
  2: ROV Observation of Sea-floor Methane Hydrate and Methane-seep-induced, Characteristic Collapse Structures (Hideaki MACHIYAMA, Ryo MATSUMOTO and Mineo HIROMATSU)
ii
  3: Sea-floor Environment and Benthos of Methane Seep Area (Hideki NUMANAMI and Ryo MATSUMOTO)
iii
  4: Slides and Debris Flow Deposits in Methane Hydrate Bearing Area (Mineo HIROMATSU, Fernando FREIRE, Mikio SATOH and Ryo MATSUMOTO)
iv
  5: Interval Velocity Anomalies Detected by 3D-seismic Analysis (Ryo MATSUMOTO and Tatsuo SAEKI)
v
  6: Observation and Analysis of Methane Plume (Chiharu AOYAMA, Maki SUZUKI and Ryo MATSUMOTO)
vi
  7: Methane Hydrate off Sakhalin, the Sea of Okhotsk (Hitoshi SHOJI, Hirotsugu MINAMI, Akihiro HACHIKUBO, Young K. JIN, Anatoly OBZHIROV, Alexander SALOMATIN and Boris BARANOV)
vii-viii