Stressing Rate Changes Associated with the 2015 Axial Seamount Eruption

Abstract:

The Ocean Observatory Initiative Cabled Array recorded high-quality ocean bottom seismic data data surrounding the April and May 2015 eruption of Axial Seamount on the Juan de Fuca Ridge. This extensive dataset includes more than 40,000 earthquakes recorded between January 2015 and September 2015. Seismicity rates varied during the inflation-deflation cycle. From the observed rate changes in microseismic activity, we are tracking the four-dimensional evolution of stress within Axial Volcano. We use the Epidemic Type Aftershock Sequence model to calculate Coulomb stress changes assuming rate and state friction (e.g. Dieterich, 1994). We plan to correlate the spatial and temporal stress changes with caldera elevation and tilt, and with vent temperature and chemistry. Where seismicity rates are driven by inflation and deflation of the magma chamber, we expect the predicted stress changes will correlate with elevation and tilt data. Where seismicity rates are governed by perturbations to hydrothermal flow, we expect stress changes to correlate with vent temperature and chemistry. Using the microseismicity we will track the importance of the inflation-deflation cycle in comparison to hydrothermal flow throughout the eruption. The extensive seismic data recorded during the eruption cycle on Axial provides a unique opportunity to investigate seafloor deformation and hydrothermal fluid flow associated with submarine volcanism.