Cowen, James P. OCE-9810026 Abstract This project is a rapid response to an seismic event on Axial seamount on the Juan de Fuca Ridge. Starting January 28, 1998, a seismic event was detected using the T-phase monitoring system developed by NOAA/PREL to access the US Navy's SOSUS arrays. Over 6000 earthquakes were detected in the first days of the event, making this the most intense seismic event yet observed in this area. The character of this seismicity is very similar to that observed at CoAxial segment and the Northern Gorda Ridge, both episodes that were later confirmed to be eruptive events. The proposal is to mount a rapid response cruise on the R/V Wecoma. The Objectives are to: (1) detect and characterize events plume(s) and other venting associated with the seismic event, (2) to deploy neutrally buoy and drifter buoys (RAFOS floats) and associated sound source array for tracking an event plume, (3) establish whether there has been a subsurface bacterial bloom, (4) advance time-series measurements of geochemical and microbial concentrations and activities in megaplume and event-initiated plumes, and (5) deploy ocean bottom hydrophones.
