Low velocity anomaly of gas hydrate-bearing sediments and in-situ measurements of gas content of deep-sea sediments

2014 Fiscal Year Final Research Report

• Project/Area Number: 24244078
• Research Category: Grant-in-Aid for Scientific Research (A)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Geology
• Research Institution: Meiji University
• Principal Investigator: MATSUMOTO Ryo 明治大学, 研究・知財戦略機構, 教授 (40011762)
• Co-Investigator(Kenkyū-buntansha): OGIHARA Shigenori 東京大学, 理学系研究科, 助教 (50214044) ; NOBORIO Kosuke 明治大学, 農学部, 教授 (60311544) ; ISHIHAMA Saeko 神奈川県立生命の星, 地球博物館・学芸部, 学芸員 (60416047) ; KAKUWA Yoshitaka 明治大学, 研究知財戦略機構, 教授 (70124667) ; TOMARU Hitoshi 千葉大学, 理学研究科, 准教授 (80588244) ; OCHIAI Hiroyuki 北里大学, 獣医学部, 講師 (90440156)
• Project Period (FY): 2012-05-31 – 2015-03-31
• Keywords: ガスハイドレート / メタンハイドレート / フリーガス / 低速度異常 / 多目的三脚ツール / 深海堆積物

Outline of Final Research Achievements

Physical properties such as Vp of deep-sea sediments could not be determined by the measurements of sediment cores recovered from the deep sea floor. This is because the properties are drastically changed due to gas escape during core recovery. Unprecedented tool mTPT, multi-purpose tripod tool, has been developed for the in-situ measurements of physical properties. The tool is made up of heavy weight and three long pipes hanging down from the weight. A transmitter is installed within a pipe and receivers in the other two pipes. The three pipes are penetrated into the sediments and the transit time between the pipes is directly measured to estimate the Vp of the sediments.
Experimental deployment on the deep-sea floor of 1000 m has successfully recorded anomalously low Vp within a few meters below the sea floor, indicating that the sediments contain significant amount of free gas. The tool provides new technology for in-situ measurements of the Vp of deep-sea sediments.

Free Research Field

堆積学　海洋地質学