Collaborative Research: Caldera Dynamics and Eruption Cycles at Axial Seamount

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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.