Collaborative Research: Monitoring hydrothermal fluids, crustal permeability and seafloor morphology in preparation for the next volcanic eruption at the East Pacific Rise, 9'50"N

东太平洋隆起(EPR)是位于东太平洋的一个快速扩张的大洋中脊。它是一个环绕地球的山脊系统的一部分，在那里，地球的地壳是由来自更深地幔的熔融入侵和随后的火山喷发形成的。当海水流经大洋地壳时，铁道部的热液喷口形成烟囱和富含金属的排放物。这些热液作用改变了大洋岩石圈和全球海洋的组成，为化学合成生态系统中极端形式的生命提供了独特的栖息地。了解次表层流动模式与地壳条件之间的耦合对于大洋中脊的几乎所有领域以及相关的地球化学和地球物理研究都至关重要。这项研究的重点是未来几年(~2020-2023年)在9°50‘N地区的EPR轴上可能发生一次新的涉及喷发或浅层岩浆侵位的岩浆事件。这一预测是基于观察到的喷口出口流体温度的上升和化学趋势。海上科学家将使用研究潜水器Alvin和/或遥控潜水器(ROV)Jason来部署仪器，并在连续三年的三次航行中收集喷口流体样本，以研究这些过程。该项目还涉及来自美国和挪威的年轻研究人员之间的合作，这将有助于加强两国研究人员之间的国际联系。研究人员还将通过在斯克里普斯海洋研究所举办的三次研讨会，为圣地亚哥联合学区制作新的教材。这次与圣地亚哥县教育办公室的合作将加强他们的环境素养倡议，并有助于为加州和全国的初中和/或高中教师创建下一代科学标准、活动和资源。该项目的研究目标集中在这样一个想法上，即未来几年(~2020-2023年)，9°50‘N地区的EPR轴线可能会发生新的岩浆事件，无论是喷发还是浅岩脉侵位。这一预测是基于喷口出口流体温度的上升和在热液喷口测得的化学趋势。这一事件的形成预计与地壳动力学的变化有关，可以在地球化学性质和对跨越多个热液喷口及其流体的潮汐强迫的热反应中观察到这种变化。具体地说，热响应和加载信号之间的相位滞后和幅度比可以用来跟踪下一次火山喷发的准备过程。为了监测岩浆再补给及其对热液流动的影响之间的关系，该项目将采用数值方法，利用自记录高温记录仪获取的流出流体温度记录中观察到的潮汐变异性。这一分析的结果将约束地壳的孔弹性性质。为了实现这些目标，该项目将收集相隔大约一年的三次连续巡航的几个相关数据集，每年有七次Alvin或Jason ROV潜水。这些数据集包括：一)喷口出口流体温度记录，每隔约15分钟记录一次；二)使用等压气密取样器从每个装有仪器的喷口采集年度流体样本；三)系泊传感器记录的潮汐压力和海流强度数据；四)使用仪器测量的喷口结构的高分辨率静态和4k分辨率视频图像；以及五)将于2019年12月使用自主水下机器人哨兵获取的近海底基线水深和侧扫数据集。这些数据将成为地球物理学家、生物学家和化学家在EPR 9°50‘N喷发工作的关键资源。这一奖项反映了NSF的法定使命，并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，被认为值得支持。

The East Pacific Rise (EPR) is a fast-spreading mid-ocean ridge located in the eastern Pacific Ocean. It is part of a globe-encircling system of ridges where the crust of the Earth is created by the intrusion of melt from the deeper mantle and consequent volcanic eruptions. Hydrothermal vents from the MOR form chimneys and columns of metal-rich emissions as seawater flows through the oceanic crust. These hydrothermal processes alter the composition of oceanic lithosphere and the global ocean, and provide unique habitats for extreme forms of life in chemosynthetic ecosystems. Understanding the coupling between sub-surface flow patterns and crustal conditions is fundamentally important for virtually all fields of mid-ocean ridge and related geochemical and geophysical research. This research project focuses on the idea that a new magmatic event involving an eruption or shallow magma emplacement, is likely to happen at the EPR axis in the 9°50’N area in the next few years (~2020–2023). This forecast is based on observed increases in vent exit-fluid temperature, and chemical trends. The scientists at sea will employ the research submersible Alvin and/or remotely operated vehicle (ROV) Jason to deploy instruments and collect vent fluid samples during three cruises over three successive years to study these processes. The project also involves a collaboration between young investigators from the USA and Norway that will help strengthen international ties between researchers in both countries. The researchers will also create new teaching materials for the San Diego Unified School district via three workshops held at Scripps Institution of Oceanography. This collaboration with the San Diego County Office of Education will enhance their Environmental Literacy Initiative, and help to create a Next Generation Science Standards,activities and resources for middle and/or high school teachers in California and nation-wide.This project's research objective focuses on the idea that a new magmatic event, either an eruption or shallow dike emplacement, is likely to happen at the EPR axis in the 9°50’N area in the next few years (~2020–2023). This forecast is based on increases in vent exit-fluid temperature and chemical trends measured at hydrothermal vents. The build-up to this event is anticipated to be associated with changes in crustal dynamics that can be observed in the geochemical properties and thermal response to tidal forcing across multiple hydrothermal vents and their fluids. Specifically, the phase lag and amplitude ratio between the thermal response and loading signal can be used to track the run-up to the next volcanic eruption. In order to monitor the relationship between magma resupply and its impact on hydrothermal fluid flow, the project will apply numerical methods to exploit the tidal variability observed in exit-fluid temperature records acquired using self-recording high-temperature loggers. The result of this analysis will constrain poroelastic properties of the crust. To accomplish these goals, the project will collect several correlative datasets on three successive cruises spaced approximately 1-year apart, with seven Alvin or Jason ROV dives each year. The datasets include i) vent exit-fluid temperature records logged at ~15 min intervals; ii) annual fluid samples from each instrumented vent using isobaric gas-tight samplers; iii) tidal pressure and current strength data logged by moored sensors; iv) high-resolution still and 4k-resolution video imagery of vent structures that are instrumented, and v) baseline near-bottom bathymetry and sidescan dataset to be acquired in December 2019 using autonomous underwater vehicle Sentry. These data will be a key resource to underpin the work of geophysicists, biologists and chemists from across the mid-ocean ridge community working at EPR 9°50’N. eruption.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.