SGER - Hydrologic Monitoring of Leaking Coseismically Active Thrusts: A Pilot Study in the Nankai Subduction Zone

摘要在该奖项下，PI将在日本南海增生楔进行一项关于构造和水文地质相互作用的试验性研究。 这项研究需要部署五个仪器，对沿着主要同震活跃的序列外逆冲断层（OOST）区的冷泉进行为期一年的监测。PI已被邀请参加为期3周的日本巡航，将调查渗漏并部署仪器。这些逆冲断层直接向下连接到孕震区，已知会泄漏流体，并且已经沿着它们沿着发现了许多渗漏。最近的观测表明，该OOST区域也是极低频（VLF）地震似乎起源的位置，可能与孕震区上倾极限附近的超慢地震有关。PI将使用已被证明能够在活跃渗漏环境中收集流体流量、温度以及水和气体化学的长期记录的仪器。通过将这些流动记录与附近的钻孔地震记录（或许还有日本的OBS记录）进行比较，PI希望澄清地下流体压力脉冲与与VLF事件相关的应力释放事件之间的关系。这项研究的更广泛影响主要来自于其与主要国际研究项目和自然灾害缓解的直接相关性。该油田是IODP NantroSeize钻井计划的重要部分。它还旨在帮助启动美国和日本科学家之间的高度合作伙伴关系。最终，我们将使用的仪器可以联网，作为长期监测系统的一部分。研究地震和海啸生成俯冲带中的断层不稳定性对人类和政治有直接影响。

AbstractUnder this award, the PIs will undertake a pilot study of the interaction of tectonics and hydrogeology at the Nankai accretionary wedge of Japan. The study entails the deployment of five instruments for one year monitoring of cold seeps along the major coseismically active out-of-sequence thrust (OOST) zones. The PIs have been invited on a 3-week Japanese cruise that will investigate the seeps and deploy the instruments. These thrusts link directly down to the seismogenic zone, are known to leak fluids, and numerous seeps have been identified along them. Recent observations indicate that this OOST region is also the location from which very low frequency (VLF) earthquakes appear to be originating that may be tied to ultra slow earthquakes near the updip limit of the seismogenic zone. The PIs will be using instrumentation that has been shown to be capable of collecting long-term records of fluid flow, temperature, and both aqueous and gas chemistry in active seep environments. By comparing these flow records to nearby borehole seismic records (and perhaps Japanese OBS records), The PIs hope to clarify the relationship between subsurface fluid pressure pulses and stress release eventsrelated to the VLF events.The broader impacts of this study come primarily through its direct relevance to major international programs of research and natural hazard mitigation. The field area is the focus of a significant portion of IODPs NantroSeize drilling program. It is also intended to help initiate a highly collaborative partnership between US, and Japanese scientists. Eventually, the instrumentation we will be using can be networked as part of a long-term monitoring system. Studying fault instabilities in an earthquake and tsunami generating subduction zone has direct human and political impact.