New insights into magma plumbing along rift systems from detailed observations of eruptive behavior at Axial volcano

The magma reservoir in geophysical volcano plumbing models is often modeled as a simple geometric volume, filled with magma of uniform properties. However, the constraints on reservoir size and magma properties in volcano roots are typically indirect and poor. Axial Seamount, a volcano at a depth of about 1500 m on the Juan de Fuca mid‐oceanic ridge in the Pacific Ocean, has both high‐resolution seismic images of its subsurface magma and detailed results from monitoring of its most recent eruption and associated seismicity and ground deformation. The 2015 eruption at Axial Seamount is the best monitored submarine eruption so far because of observations made possible by the Ocean Observatories Initiative, and seismic imaging of magma at this volcano is better than in most other environments because of advanced analysis of extensive seismic reflection profiling at sea and the relatively simple volcano structure. This allows new understanding compared to findings from earlier observations from monitored rifting episodes on land. Geophysical magma plumbing models, in general, may need to allow for more complexities, namely, spatial heterogeneities in magma composition, melt content, and location of major volume changes within a single magma dominated crustal volume during eruptions. Key Points The Ocean Observatories Initiative monitored the 2015 submarine eruption and rifting at Axial volcano in unprecedented details Geophysical magma plumbing models, in general, may need to allow for more complexities A “magma domain” beneath volcano, tapped in a single eruption, may have magma pockets of variable composition and connectivity