Collaborative Research: Earthquake Catalog and Waveform Analysis to Assess the Evolution of Axial Seamount Surrounding the 2015 Eruption

Axial seamount is an active submarine volcano located off the west coast of the US on the Juan de Fuca midocean ridge spreading center. Axial has recently been instrumented for continuous real-time data monitoring as part of the cabled ocean observatory network of the NSF-sponsored Ocean Observatory Initiative (OOI) that includes high-quality ocean bottom seismic data, as well as an unrivaled set of seafloor geodetic and hydrothermal measurements. The seamount has erupted periodically in the past but the most recent eruption in April/May 2015 was captured by the local seismic network and provides a unique dataset with which to investigate the eruption and magmatic mechanisms associated with submarine volcanoes. The project will analyze the evolution of earthquake properties and statistical patterns in space and time, as well as how these changes are correlated with deformation and hydrothermal outputs throughout the eruption cycle. These data will be used to track changes in stress and the movement of magma within the volcanic edifice, leading to a better understanding of the mechanics of submarine volcanoes and the dynamics of eruptions on the seafloor. This project takes advantage of the recently enabled OOI Axial seamount cabled array data portal and will contribute to scientific infrastructure for undersea monitoring. The project provides research experience for community college students, undergraduates and graduate students, and training for middle-school science teachers in the areas of earthquake physics and submarine volcanic processes.

This project will utilize the compiled Axial Seamount seismic catalog and carry out waveform analysis to assess the evolution of the volcanic system before, during and after the April and May 2015 eruption including the many linkages between earthquakes, seafloor deformation and hydrothermal activity. Stress states will be inferred by monitoring changes in seismicity rate and variations in earthquake statistical patterns. The strength of the faults and/or the movement of fluids will be constrained through earthquake source parameter studies. This project will advance three technical goals: 1) Study the evolution of stress within the volcanic crust through the 2015 eruption at Axial Seamount using a novel combination of techniques, including seismicity/stressing rate changes, earthquake stress drop measurements and seismic b-value studies. 2) Investigate the response of fault systems within the caldera to dynamic stresses in the context of their local stressing history, and by incorporating hydrothermal time series observations that provide new constraints on the role of fluids in dynamic triggering. 3) Explore the exceptional record of explosive acoustic events associated with the 2015 eruption. Although there is increasing evidence that explosive volcanism is common in the deep-sea, there are few direct observations. Understanding the distribution and scaling of these signals may transform our views on eruption dynamics in mid-ocean ridge environments.