5 YEARS OF GROUND DEFORMATION MONITORING ON AXIAL SEAMOUNT USING A BOTTOM PRESSURE RECORDER

The results of five years of pressure measurements collected by a Bott om Pressure Recorder deployed within the summit caldera of Axial Seamo unt, on the central Juan de Fuca Ridge, are interpreted for monotonic offsets related to vertical seafloor movements. Results indicate five significant subsidence events during the observation period (3.7 years ), or an average of 1.35 events per year. The displacements range from 3-10 cm with durations of 10-14 days. These results indicate an activ e volcanic system and can be viewed as positive evidence for future at tempts at seafloor volcanic observatories and response to active event s on oceanic ridge crests. Advanced instrumentation based on multiple sensors has been deployed at the site to reinforce the results of this pilot experiment.