Phase 2 of Enhancements to the OOI Cabled Array at Axial Seamount

轴向海山是美国太平洋西北部最活跃的火山，它恰好位于水下，距离俄勒冈海岸约300英里。在过去的20年里，它已经喷发了三次，我们知道，在接下来的几年里，它可能会再次喷发。因此，它是美国国家科学基金会海洋观测倡议电缆阵列（OOI-CA）在东北太平洋进行长期监测的理想地点，这是世界上最先进的水下火山观测站。OOI-CA之前的监测表明，轴向海山有一个非常可重复的膨胀和收缩周期，这被用来预测火山爆发。该项目将在未来5年内在轴向海山部署额外的监测仪器，这将使我们能够更好地预测下一次喷发，将改进火山内岩浆供应和储存的模型，并将测试深海海洋环境受到海底喷发影响的想法。这项研究符合国家和社会的利益，因为它将提高我们对火山是如何工作的理解，以及如何更好地预测火山喷发（包括陆地和水下）。该项目将资助对OOI电缆阵列的仪器进行适度、经济、及时的改进，以解决现有基础设施中的一些缺陷。其中一个关键因素是在海底部署电导率、温度、深度（CTD）仪器来测量盐度的变化，以验证热液盐水在火山喷发期间从山顶火山口释放的假设。具体来说，该项目将：(1)保留一个已经部署在OOI-CA上的海底CTD再运行5年；(2)在OOI-CA上的其他两个地点增加两个额外的海底CTD，以扩大空间覆盖范围和所需的冗余；(3)建造8个Mini-BPR（底部压力记录仪）传感器，以取代其他仪器，这些仪器是长期大地测量监测的一部分，可以增强OOI-CA的观测结果。这些对轴向海山监测工作的改进将在轴向海山下一次喷发（目前预计在2020-2022年之间）期间及时部署，这将有助于我们进一步了解活跃玄武岩火山的浅层岩浆供应和储存系统，导致和触发喷发的过程，以及海底喷发对热液系统和化学合成生态系统的影响。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Axial Seamount is the most active volcano in the U.S. Pacific Northwest - it just happens to be located underwater, about 300 miles off the Oregon coast. It has erupted three times in the last 20 years, and we know it is building toward another eruption in the next few years. Consequently, it is an ideal site for long-term monitoring with the National Science Foundation's Ocean Observatory Initiative Cabled Array (OOI-CA) in the Northeast Pacific ocean, which is the world's most advanced underwater volcano observatory. Previous monitoring with the OOI-CA has shown that Axial Seamount has a very repeatable cycle of inflation and deflation that has been used to forecast eruptions. This project will deploy additional monitoring instruments at Axial Seamount over the next 5 years and these will allow us to better forecast the next eruption, will improve our models of magma is supplied and stored within the volcano, and will test ideas about the deep-sea marine environment is impacted by submarine eruptions. This research serves the national interest and society because it will improve our understanding of how volcanoes work and how eruptions can be better forecast (both on land and underwater).This project will fund modest, cost-effective, and timely enhancements to the instrumentation on the OOI Cable Array to address some deficiencies in the existing infrastructure. A key element will be deploying Conductivity, Temperature, Depth (CTD) instruments on the seafloor to measure changes in salinity to test the hypothesis that hydrothermal brines are released in the summit caldera during some eruptions. Specifically this project will: (1) keep one seafloor CTD that is already deployed operating on the OOI-CA for 5 more years, (2) add two additional seafloor CTDs at two other sites on the OOI-CA for expanded spatial coverage and needed redundancy, and (3) build eight Mini-BPR (bottom pressure recorder) sensors to replace other instruments that are part of the long-term geodetic monitoring that augments the observations from the OOI-CA. These enhancements to the monitoring effort at Axial Seamount will be available in time to be deployed during the next eruption at Axial Seamount (currently expected between 2020-2022), which will help to increase our understanding of the shallow magma supply and storage systems at active basaltic volcanoes, the processes that lead to and trigger eruptions, and the impacts of submarine eruptions on hydrothermal systems and chemosynthetic ecosystems.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.