Bronder, Christine2021-09-282021-09-282021http://hdl.handle.net/1773/47754Mid ocean ridges are large interruptions in the expansive abyssal plains that dominate ocean basins. Volcanically active ridges release heat and chemicals into the surrounding ocean through hydrothermal plumes. Benthic organisms are dependent on these plumes for nutrients and distribution of their larvae. Quantifiable changes in hydrothermal plumes have been documented in response to volcanic eruptions. These plumes experience increases in fluid temperature and rise height after eruptions and become event plumes. This study investigates the effects on circulation from the 2015 eruption at Axial Seamount: a submarine volcano located along the Juan de Fuca Ridge, 300 miles off the coast of Oregon. After the eruption, an unusual temperature increase was measured within the summit caldera. This increase is unique compared to other eruptions in that it is widespread, uniform, and has a large amplitude of 0.6 to 0.7 °C. Two hypotheses exist for the temperature anomaly: a large brine layer was expelled from the subsurface after the eruption, and a neutrally buoyant event plume formed above a lava flow and was advected above the summit. Since no salinity data is available, I evaluate the two hypotheses using the mean flow direction, magnitude, and variation of currents measured at a site within the caldera. There was an abnormal sustained flow to the southeast lasting 12 days with high speed coinciding with the rising temperature. This observation is consistent with the movement of a large volume of warm fluid. The increase in standard deviation and by proxy, turbulence, are not significant enough in the presence of increased flow speed to discriminate between a brine layer or event plume as the cause.Axial SeamountOcean circulationSubmarine volcano