FATE OF EVENT HYDROTHERMAL PLUMES ON THE JUAN-DE-FUCA RIDGE

Current meter moorings were deployed in August 1993 at the megaplume site of the June 1993 seismic event on the CoAxial segment of the Juan de Fuca Ridge and were recovered in April 1994. Record-averaged flow was about 2 cm/s across axis, which is sufficiently large to advect plumes off axis in a few days. During July two megaplumes (1800 m level) disappeared between repeated CTD rows. A deeper plume (2150 m) had a relatively strong signature during August and extended southeastward in agreement with the observed flow. A CTD tow along the east flank of Axial Volcano did not locate remnants of the megaplumes but did find deeper plumes which could have come from off-axis advection from the CoAxial sources followed by southward advection along the east side of ridge.