MeBoCORK: Development of borehole observatories for MeBo (MARUM Meeresboden- Bohrgerät): Application to the seismogenic Nankai Trough subduction zone, Japan

地球上大约90%的地震矩在通常具有破坏性的俯冲带地震（EQ）中释放。在综合大洋钻探计划（1 ODP）中，以“南海海槽孕震带实验”（NantroSEIZE）为形式的多学科考察，对活动会聚边缘沿着地震成因的研究起着关键作用。迄今为止，8个考察队（1 ODP考察队314-316、319、322、326、332-333）沿沿着一条从传入板块穿过前缘增生棱柱到弧前盆地的断面钻探了12个地点。在不久的将来，最深的孔将利用立管钻探进入俯冲巨型逆冲断层的孕震部分。支持者参加了三次NanTroSEIZE探险，最近一次是作为联合首席科学家监督成功回收迷你软木塞和安装迷你软木塞和完整的软木塞天文台（实验332）。本提案旨在达到两个主要的科学里程碑：（i）除了1 ODP钻孔观测网络的德国部分（即第319和332航段期间的小型COLK加上对整个COLK的一些贡献）之外，我们希望将长期监测工作扩展到站点C 0009向陆地约30公里处的活泥火山。这些特征携带着天然气水合物和深层流体，很可能进入海底以下几公里深处的孕震区，而且还覆盖着高应变和锁定板块边界逆冲的地区。(ii)第二个目标是开发一个智能MeBo（MARUMMeeresboden-Bohrgerät）CORK天文台，安装在其中两个泥火山上。这些观测站将是独立的，并监测孔隙压力和温度，作为钻孔终端深度附近应变和流体流动的代表。它们的液压管线还可用于地球化学（微生物取样器）和微生物（FLOCS装置）监测和取样。MeBo智能观测站的工程效果的根本原因在新的IODP科学计划中被发现，其中MeBo等专业钻机被讨论为ECORD在2013-2023年的贡献。到目前为止，CORKs或其他复杂的长期设备仅限于DVs Joides Resolution和Chikyu，然而，我们在这里为多功能，多学科的MeBo钻孔仪器提供了一个负担得起的解决方案。拟议的系统将由MeBo单独安装，数据可由机会船检索。由ROV部署和回收的海底延伸（在预期的IODP考察期间和/或之后）可以增加能力和有效载荷，因此代表了十多年监测的手段。数据恢复将从机遇号船上进行，因此经常可以进行。已为南开泥火山油田的MeBo钻井和海底钻探装置提供资金（RV索内号2012年夏季SO 222巡航），并作为实物捐助纳入该项目。

Approximately 90% of the seismic moment on Earth is released in often devastating subduction zone earthquakes (EQs). In the Integrated Ocean Drilling Program (lODP), the study of seismogenesis along an active convergent margin plays a key role in the form of a multi-expedition effort named "NanTroSEIZE" (Nankai Trough Seismogenic Zone Experiment). To date, eight expeditions (lODP Expeditions 314-316, 319, 322, 326, 332-333) drilled 12 sites along a transect from the incoming plate across the frontal accretionary prism to the forearc basin. In the near future, the deepest hole will tap into the seismogenic portion of the subduction megathrust using Riser drilling. The proponent participated in three of the NanTroSEIZE expeditions, most recently as co-chief scientist overseeing the successful recovery of a mini-CORK and the installation of a mini-CORK and a full CORK observatory (Exp 332). This proposal aims lo reach two major scientific milestones:(i) In addition to the German component of the lODP borehole observatory network (i.e. mini- CORKs during Legs 319 and 332 plus some contribution to the full CORK), we want to extend the long-term monitoring efforts to active mud volcanoes some 30 km landward of Site C0009. These features carry gas hydrates and deep-seated fluids, most likely tapping into the seismogenic zone at a depth of several km below seafloor, and are also overlying an area of high strains and a locked plate boundary-thrust.(ii) The second goal is to develop a smart MeBo (MARUM Meeresboden-Bohrgerät) CORK observatory to be installed in two of these mud volcanoes. These observatories will be self-contained and monitor pore pressure and temperature as proxies for strain and fluid flow near terminal depth of the borehole. Their hydraulic lines can further be used for geochemical (osmo-sampler) and microbiological (FLOCS units) monitoring and sampling.The underlying reason for the engineering effon of smart observatories for MeBo is founded in the new lODP Science Plan where specialist rigs such as MeBo are discussed as ECORD's contribution from 2013-2023. So far, CORKs or other sophisticated long-term devices were restricted to DVs Joides Resolution and Chikyu, however, we here present an affordable solution for versatile, multi-disciplinary MeBo borehole instruments. The proposed system is to be installed by MeBo alone and data can be retrieved by ships of opportunity. A seafloor extension, to be deployed and recovered by ROVs (during and/or after the anticipated lODP expedition) can add capability and payload, and hence represent the means for more than decade of monitoring. Data recovery will be from ships of opportunity and hence frequently possible.Funding for MeBo drilling and ROV installations in the Nankai mud volcano field has already been granted (RV Sonne cruise SO222 in summer 2012) and is brought into the project as in kind contribution.