Collaborative Research: Slow-Slip and Fluid Flow Response Offshore New Zealand -Probing The Nature Of The Margin Hydrogeochemical System

合作研究：新西兰近海慢滑移和流体流动响应 - 探索边缘水文地球化学系统的性质

• 批准号: 1753665
• 负责人: Marta Torres
• 金额: $ 49.72万
• 依托单位: Oregon State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-09-01 至 2023-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1753665&HistoricalAwards=false
• 关键词: Collaborative; Research; Slow; Slip; Fluid

Observations at subduction zones over the past two decades have revealed a range of modes by which stress is released on the plate boundary, including periodic slow slip behavior. Slow slip events occur at a rate intermediate between long-term tectonic plate motion and the fast slip velocity that occurs during earthquakes. Thus, slow slip is thought to span the transition between stable slip and the stick-slip process that generates earthquakes. An important mechanism that could cause the transitions in slip style is the evolution of pressure along the fault that is generated by the accumulation and release of fluids. There is a concerted and extensive international sampling and monitoring effort to understand slow slip at the Hikurangi margin offshore New Zealand. A missing piece in this effort is the sampling and monitoring of fluids along seafloor fault zones over a long enough period of time to capture a slip event. This project will address this problem and will provide a two-year continuous record of fluid flow rate and composition over the time frame of the next expected large slow slip event. The project will add value to other ongoing NSF-funded programs at this margin such as scientific ocean drilling and seismic surveys aimed at understanding slow slip events. From both the scientific and societal perspectives, results from this project will contribute to our understanding of earthquake activity not only offshore New Zealand but worldwide. This project has a large component of international collaboration. The project supports the training of graduate and undergraduate students. This project addresses the GeoPRISMS Program's Subduction Cycles and Deformation Initiative Science Plan by testing interrelationships between fluid production, fluid flow, and slow slip at the Hikurangi margin off New Zealand. At the Hikurangi margin, the recognition of dramatic changes in the along-strike depth distributions of slow-slip events (SSEs) and their recurrence intervals, interseismic coupling, inferred pore pressure, and other subduction-related parameters have resulted in a concerted international effort to acquire seismological, geodetic, other geophysical, and geomechanical data. This project will complement and extend these efforts by providing 1) a two-year continuous record of fluid flow rate and composition over the timeframe of the next expected large SSE; 2) information on the present background state of fluid flow and how it relates to inferred overpressure along the plate boundary; and 3) comparative geochemical and hydrologic data between the northern and southern sections of the margin. The work plan combines ship operations and Remotely Operated Vehicle (ROV) surveys in a nested approach to constrain the margin-wide fluid flow distribution. Coring, heat flow measurements, and benthic fluid flow meter deployments will target fault zones and off-fault locations from the deformation front to the shelf-break. Continuous fluid flow rate measurements at off-fault locations will quantify the fluid flow response to local volumetric strain during slip, and comparative data at fault zones will provide information on the hydrologic responses to slip.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

过去二十年对俯冲带的观测揭示了板块边界上应力释放的一系列模式，包括周期性的慢滑移行为。慢滑移事件发生的速度介于长期板块运动和地震期间发生的快滑移速度之间。因此，慢滑移被认为跨越了稳定滑移和产生地震的粘滑过程之间的过渡。可能导致滑移类型转变的一个重要机制是沿断层的压力演化，该压力是由流体的积累和释放产生的。国际上正在开展协调一致的广泛采样和监测工作，以了解新西兰近海希库朗吉边缘的缓慢滑移情况。这项工作中缺少的一个部分是在足够长的时间内对海底断层带沿线的流体进行采样和监测，以捕获滑动事件。该项目将解决这个问题，并将在下一个预期的大型慢滑移事件的时间范围内提供为期两年的流体流速和成分的连续记录。该项目将为其他正在进行的国家科学基金会资助的项目增加价值，例如旨在了解慢滑动事件的科学海洋钻探和地震调查。从科学和社会角度来看，该项目的结果将有助于我们了解新西兰近海乃至全世界的地震活动。该项目有很大一部分是国际合作。该项目支持研究生和本科生的培训。该项目通过测试新西兰附近 Hikurangi 边缘的流体产量、流体流动和缓慢滑移之间的相互关系，解决了 GeoPRISMS 计划的俯冲循环和变形倡议科学计划。在希库朗吉边缘，人们认识到慢滑移事件（SSE）沿走向深度分布及其复发间隔、震间耦合、推断孔隙压力和其他俯冲相关参数的巨大变化，导致国际社会共同努力获取地震、大地测量、其他地球物理和地质力学数据。该项目将通过以下方式补充和扩展这些努力：1）在下一个预期的大型 SSE 时间范围内提供为期两年的流体流量和成分连续记录； 2）有关当前流体流动背景状态及其与推断的沿板块边界的超压的关系的信息； 3) 边缘南北段地球化学和水文数据对比。该工作计划以嵌套方式将船舶操作和遥控潜水器（ROV）调查结合起来，以限制边际范围内的流体流量分布。取芯、热流测量和海底流体流量计部署将针对从变形前沿到陆架断裂的断层带和断层外位置。断层外位置的连续流体流量测量将量化滑动期间流体流动对局部体积应变的响应，断层带的比较数据将提供有关滑动的水文响应的信息。该奖项反映了 NSF 的法定使命，并被认为是有价值的通过使用基金会的智力优势和更广泛的影响审查标准进行评估来获得支持。