Prospecting for hydrothermal vents using moored current and temperature data: Axial Volcano on the Juan de Fuca Ridge, northeast Pacific

Tidal and inertial currents and profuse hydrothermal discharge at recently erupted Axial Volcano, Juan de Fuca Ridge, cause relatively large and rapid temperature (T) changes in the near-bottom water column. Measurements show short-term T variations of as much as 0.13 degreesC at 30 m and 0.18 degre esC at 150 m above bottom and currents that have strong tidal components an d means of 3-5 cm s(-1). Locations and magnitudes of the hydrothermal sourc es leading to the observed T variations have been inferred via an inverse c alculation. Results imply noncongruent source regions around the mooring si te for plumes from low- and high-buoyancy flux sources. Water column and se afloor observations in the volcano's caldera region generally support the d istribution of source types and sites inferred. A high-buoyancy flux, ephem eral venting site, unexpected on the eastern shoulder of the volcano, is al so indicated by the inverse calculation and supported by water-column surve y data. Over the O(10 km(2)) calculation region, heat flux from low- buoyan cy hydrothermal sources is apparently less than heat flux from high-buoyanc y hydrothermal sources, a result that is in disagreement with previous repo rts on the balance of heat flux between vent source types.