Hydrothermal vent fluid perturbations related to seismic activity at Axial Seamount, Juan de Fuca Ridge

Abstract

Mid-ocean ridges are dynamic environments that transfer the largest amount of heat and chemicals from the Earth’s lithosphere to the hydrosphere. Continuous observations of the changes in mid-ocean ridge environments over long time scales are difficult. Axial Seamount is located on the southern part of the Juan de Fuca Ridge and experiences frequent volcanism and seismicity with past eruptions occurring in 1998, 2011, and 2015. To better understand mid-ocean ridge processes, a wide assortment of instruments are deployed across the Axial Seamount caldera as part of the Ocean Observatories Initiative. These instruments continuously measure seismic and hydrothermal vent field activity including: (1) the hypocenter and moment magnitude of each seismic event (2) hydrothermal vent fluid temperature and chloride concentration from a chimney located in the southern part of the caldera. This study explores the correlation between seismic events and temporal changes in temperature and chloride concentration of hydrothermal vent fluid. Results suggest that there is a long-term correlation between an increase in frequency of seismic events and an increase in hydrothermal vent fluid temperature at this location. This may be signaling more contact between circulating hydrothermal fluids and magma. Increased magma supply and increasing seismicity may indicate that the next eruption of Axial Seamount will experience lava flows in the southern part of the caldera, similar to 1998 and 2011. Further monitoring of the hydrothermal vent fluids before, during, and after the next eruption could provide more insight into the link between hydrothermal vent field activity, earthquakes, and volcanism.