Rate of displacement and recurrence time of earthquake of the submarine active fault off Tokai

东海海域海底活动断层的位移速率和地震重现时间

• 批准号: 11309002
• 负责人: TOKUYAMA Hidekazu
• 金额: $ 26.29万
• 依托单位: The University of Tokyo
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (A)
• 财政年份: 1999
• 资助国家: 日本
• 起止时间: 1999 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11309002/
• 关键词: Submarine active fault; Deep Tow survey; Enshu Fault system; High resolution underwater positioning system; Piston core; Responder; decollement; the paleo-Zenisu ridge; 遠州断層; 高精度水中測位法; ピストン・コアラー; リニアメント; 巨大地震; 活断層; 3次元・マルチチャンネル音波探査; 海底音響画像

The objectives of this research program is 1)to establish the method of deep-sea active fault surveying system(integration of high resolution underwater positioning system + deeptow surveying system, and high resolution underwater positioning system + pinpoint sampling system from oceanfloor),and 2) to determine the rate of offset of the active faults off Tokai and the recurrence time of great earthquake using the method of deep-sea active fault surveying system. In the first two years, we spent our time to construct new survey method.In 2001, we applied our new method to the Enshu fault system located in Kumano Basin using Hakuho-maru. The Enshu fault system is characterized by dextral fault with vertical displacement and mudvokanoes are aligned on the fault. We can identify displacements on the mudvolcanoes induced by fault movement.As a first step, we performed remote sensing survey across the Enshu fault system using a high resolution underwater positioning system + deeptow surveyi … More ng system, and obtained high resolution bathymetric map with a 2m counter, backscattering image of ocean floor, and subbottom cross section across the Enshu Faults system. Next, we selected two position for sampling where the rate of displacement is likely to be calculated based on the remote sensing data, and performed piston core sampling using responders attached on piston corer.The operation to make the piston core approach to the intended sampling point with high accuracy requires a high ship navigation technique in case of no remote operation capability installed on the piston core. But the high ship navigation technique of the crew members of Hakuho-maru enable to take samples from the intended points.The results of core sample analysis revealed, we can not estimate the recurrence time of great earthquake, becausecorrelated layers are not identified hi the cores obtained from the two sites. So, we tried to estimate the recurrence time of great earthquake based on the event time of mud vokano eruption, assuming that the mud eruption corresponds with the earthquake event inducing the displacement of fault. Isotropic age determination revealed that the youngest age of the mud eruption event is 23KMa. So, we can not estimate the recurrence time of earthquake.We applied 3D pre-stack depth migration process to the 3D MCS data sets obtained from Kodaiba fault system in order to clarify the structural relationship between surface manifestation of the Kodaiba fault system and the deep seated decollement(seismogenic zone? ). The results of the process suggests that 1)the decollement is characterized by high reflectivity in a range of 5km from the point where the Kodaiba fault system merges with decollement(seismic nuclear? ), 2) the decollement is identified not continuously but intermittently, and 3)subducted ridge(the paleo-Zenisu ridge) is identified beneath the lower slope. Less

深海主动故障测量系统水海报定位系统 + DeepTow测量系统的目标以及高分辨率的水下定位系统 +从海底的Pinpoint采样系统，以确定使用大地震的主动断层速率方法是在最初的两年中。我们可以识别出故障运动引起的泥伏山的位移。作为第一步，我们使用高分辨率的水下定位系统 + OW Suraveri…更多NG系统进行了远程测量，并获得了高分辨率的测深图，并使用了2M ，海底的反向散射图像，和subottom跨越ENSHU断层系统。使活塞核心接近的操作是预期的samproch tecuracy需要在活塞核心上安装远程操作的高船导航技术。预期的点。核心样本分析被启发出来，我们无法估计颗粒状的递归时间未识别出从两个坐着获得的核心。爆发，泥浆质量事件的泥浆质量确定的显示。从Kodeiba断层系统获得的3D MCS数据集，以便在kodeiba断层系统的表面表现和深度座位的座位上（地震区域？）。距Kodaiba断层Syy茎与脱土融合（地震核？）的位置的反射率在5公里的范围内，2）脱土的识别不是连续而不是间歇性的，并且3个俯冲的山脊（Paleo-Zenisu Ridge）确定了较低的Benneat。斜率

项目成果

Wonn Soh, Hidekazu Tokuyama: "Rejuvenation of submarine canyon associated with ridge subduction, Tenryu Canyon, off Tokai, central Japan"Marine Geology. 187(1-2). 203-220 (2002)

Wonn Soh、Hidekazu Tokuyama：“与山脊俯冲有关的海底峡谷的复兴，日本中部东海附近的天龙峡谷”海洋地质学。

芦 寿一郎: "熊野沖南海トラフ付加プリズムの地質と構造と冷湧水"深海研究. 20(in press). (2002)

Juichiro Ashi：“熊野附近南海海槽增生棱镜的地质和结构以及冷泉水”深海研究 20（出版中）。

Juichiro Ashi: "Mass Balance of the subduction zone in relation to methane hydrate and cold seepage activity"Chikyu Monthly. 32(Special Volume). 122-129 (2001)

Juichiro Ashi：“俯冲带的质量平衡与甲烷水合物和冷渗活动的关系”地球月刊。

徳山 英一: "相模湾・駿河湾の湧水活動"海洋と生物. 141. 290-293 (2002)

德山荣一：“相模湾和骏河湾的春季活动”海洋和生物学 141. 290-293 (2002)。

氏家由利香: "琉球海溝・南海トラフ域におけるマッドダイアピルの活動,プレート沈み込み帯における物質循環-付加体の役割-"月刊地球. 号外(32). 206-213 (2001)

Yurika Ujiie：“琉球海沟/南海海槽地区的泥底辟活动，板块俯冲带的物质循环——增生体的作用”月刊特刊（32）（2001）。