Collaborative Research: Caldera Dynamics and Eruption Cycles at Axial Seamount

合作研究：轴向海山的火山口动力学和喷发周期

• 批准号: 1950996
• 负责人: William Wilcock
• 金额: $ 41.13万
• 依托单位: University of Washington
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-07-15 至 2024-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1950996&HistoricalAwards=false
• 关键词: Collaborative; Research; Caldera; Dynamics; Eruption

Volcanic eruptions are one of the most important processes that shape the Earth’s surface. However, eruptions are difficult to study up close because they are so destructive. The deep seafloor provides an opportunity to collect detailed observations of eruptions immediately atop a volcano. Since 2014, the NSF Ocean Observatories Initiative has operated a cabled observatory in the southern half of the summit caldera of Axial Seamount, an active volcano located 300 miles off the coast of Oregon. In 2015, the volcano erupted and the records from cabled instruments provided many insights. Among these insights were improvements in forecasting eruptions. Axial Seamount is rapidly inflating, and another eruption is now predicted in a few years. This proposal will operate 15 remote seafloor instruments for earthquake detection. Over 2 years the project will seek to record the next eruption. These new observations will improve understanding of how magma and fractures interact in volcanoes. Such interactions create the pathways of magma to the seafloor. This experiment is part of a broader effort in the volcano science community to develop Community Experiments. These experiments include different kinds of eruptions. Through the comparison of the different eruptions scientists will improve the understanding of volcano hazards. The data from this project will be available to all of the public. Among the science community this data sharing will help scientists interpret geological, hydrothermal and biological observations from submarine volcanoes.Axial Seamount is a submarine volcano at the intersection of the Cobb hotspot and the Juan de Fuca ridge that erupted in 1998, 2011 and 2015. The 2015 eruption was captured in real time by the instrumentation on Ocean Observatories Initiative (OOI) Cabled Array shortly after the observatory came online. The geophysical observations yielded new insights into eruption forecasting, the dynamics of caldera ring faults, and the generation of explosive signals on the seafloor as lava erupts. However, the small footprint of the 7-station cabled seismic network limited the spatial extent of well-resolved earthquake locations to the southern portion of the caldera and the short duration of observations prior to the eruption complicated the search for precursory signals. As a result, there are unresolved questions related to the dynamics of the northern caldera, the interactions of the caldera ring faults and eruptive rifts, the impacts of magmatic processes during eruption cycle on the time-dependent seismic structure of the upper crust, and the links to deeper magmatic processes. This project will support a 2-year field experiment in the predicted time window of the next eruption that will deploy 15 autonomous ocean bottom seismographs (OBS) to extend seismic coverage of the cabled network to cover the whole caldera and portions of the south and north rifts. The open access data will be used to create earthquake catalogs and support a variety of studies to constrain the dynamics of the whole caldera, characterize the interaction the eruptive dikes with the caldera, observe the spatiotemporal evolution of shallow magmatic and tectonic process and search for signals associated with deeper magmatic processes. It will address three hypotheses, that: 1) magmatic processes related to the shallow reservoir exert primary control on caldera and rift structure; 2) the complex shallow reservoir geometry reflects and affects the evolution of magma transport and storage; and 3) magma from the deeper part of the system can be rapidly mobilized and interact with the shallow reservoir over short timescales (weeks/months).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.

火山喷发是塑造地球表面最重要的过程之一。然而，火山喷发很难近距离研究，因为它们具有如此大的破坏性。深海底提供了一个收集火山喷发的详细观测资料的机会。自2014年以来，美国国家科学基金会海洋观测站倡议在轴心海山山顶火山口的南半部运营了一个电缆观测站，这是一座位于俄勒冈州海岸300英里外的活火山。2015年，火山爆发，电缆仪器的记录提供了许多见解。这些见解包括对火山喷发预测的改进。轴向海山正在迅速膨胀，预计几年后将再次喷发。该提案将操作15个远程海底地震探测仪器。该项目将在两年多的时间里记录下下一次火山喷发。这些新的观察结果将提高对火山岩浆和裂缝如何相互作用的理解。这种相互作用创造了岩浆通往海底的通道。这个实验是火山科学界发展社区实验的更广泛努力的一部分。这些实验包括不同类型的喷发。通过对不同喷发的比较，科学家将提高对火山危害的认识。这个项目的数据将对所有公众开放。在科学界，这种数据共享将帮助科学家解释海底火山的地质、热液和生物观测结果。轴向海山是一座海底火山，位于科布热点和胡安·德·富卡山脊的交汇处，于1998年、2011年和2015年喷发。海洋观测站倡议（OOI）电缆阵列上的仪器在观测站上线后不久实时捕捉到了2015年的火山喷发。地球物理观测为火山喷发预测、火山口环断层动力学以及熔岩喷发时海底爆炸信号的产生提供了新的见解。然而，7个台站电缆地震台网的占地面积小，限制了在破火山口南部获得良好分辨率的地震位置的空间范围，而且火山爆发前的观测时间短，使得寻找前兆信号变得复杂。因此，关于北部火山口的动力学、火山口环断层与喷发裂谷的相互作用、喷发周期中岩浆过程对上地壳地震结构的影响以及与更深岩浆过程的联系等问题仍存在未解决的问题。该项目将支持一项为期两年的现场实验，在下一次火山喷发的预测时间窗口内，将部署15台自主海底地震仪（OBS），以扩大电缆网络的地震覆盖范围，覆盖整个火山口以及南北裂谷的部分地区。这些开放获取的数据将用于创建地震目录，并支持各种研究，以约束整个火山口的动力学，表征喷发岩脉与火山口的相互作用，观察浅层岩浆和构造过程的时空演化，并寻找与深层岩浆过程相关的信号。本文将提出三个假说：1)与浅层储层有关的岩浆作用对破火山口和裂谷构造起主要控制作用；2)复杂的浅层储层几何形态反映并影响着岩浆搬运与储存的演化；3)系统深处的岩浆可以在短时间尺度（数周/数月）内迅速动员并与浅层储层相互作用。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。