Collaborative Research: Caldera Dynamics and Eruption Cycles at Axial Seamount

火山爆发是塑造地球表面的最重要的过程之一。然而，火山爆发很难近距离研究，因为它们具有很大的破坏性。深海海底提供了一个机会，可以收集火山顶部喷发的详细观测资料。 自2014年以来，NSF海洋观测站计划在Axial Seamount火山口的南半部运营了一个有线观测站，Axial Seamount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，有线仪器的记录提供了许多见解。这些见解包括预测火山爆发的改进。轴海山正在迅速膨胀，现在预测几年内会有另一次喷发。 该提案将操作15台海底遥测仪器进行地震探测。该项目将在2年内记录下下一次喷发。 这些新的观察结果将提高对岩浆和裂缝如何在火山中相互作用的理解。这种相互作用创造了岩浆流向海底的通道。 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。 该项目的数据将向所有公众开放。在科学界，这种数据共享将有助于科学家解释海底火山的地质，热液和生物观测。轴向海山是科布热点和胡安·德富卡海脊交汇处的海底火山，于1998年，2011年和2015年爆发。2015年的火山爆发是在观测站上线后不久，由海洋观测站倡议（OOI）电缆阵列上的仪器在真实的时间内捕获的。地球物理观测为火山喷发预测、火山口环断层的动态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站电缆地震网络的占地面积小，限制了火山口南部的良好分辨的地震位置的空间范围和喷发前的观测持续时间短，复杂的搜索地震信号。因此，有未解决的问题有关的动力学的北方破火山口，破火山口环断层和喷发裂缝的相互作用，在喷发周期的上地壳的时间相关的地震结构的岩浆过程的影响，以及更深的岩浆过程的联系。该项目将支持在预测的下一次火山爆发时间窗内进行为期两年的实地实验，该实验将部署15个自主海底地震仪，以扩大电缆网络的地震覆盖范围，以覆盖整个破火山口以及南北裂谷的部分地区。开放获取的数据将用于创建地震目录，并支持各种研究，以约束整个破火山口的动力学，表征喷发岩墙与破火山口的相互作用，观察浅层岩浆和构造过程的时空演化，并寻找与更深岩浆过程相关的信号。 本文提出了三个假说：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运移和储存的演化;来自系统深部的岩浆可以在短时间内迅速流动并与浅部储层相互作用该奖项反映了NSF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。

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.