HR: 0800h
AN: G51A-0070    [Abstracts]
TI: Monitoring vertical deformation at Axial Seamount since its 1998 eruption using deep-sea pressure sensors
AU: * Nooner, S L
EM: snooner@ucsd.edu
AF: Scripps Institution of Oceanography, University of California San Diego 9500 Gilman Dr., Dept. 0225, La Jolla, CA 92093-0225 United States
AU: Chadwick, W W
EM: bill.chadwick@noaa.gov
AF: Oregon State University/NOAA, Hatfield Marine Science Ctr. 2115 Oregon State Univ. Dr., Newport, OR 97365-5258 United States
AU: Zumberge, M A
EM: zumberge@ucsd.edu
AF: Scripps Institution of Oceanography, University of California San Diego 9500 Gilman Dr., Dept. 0225, La Jolla, CA 92093-0225 United States
AU: Embley, R W
EM: embley@pmel.noaa.gov
AF: NOAA/Pacific Marine Environmental Laboratory, Hatfield Marine Science Ctr. 2115 Oregon State Univ. Dr., Newport, OR 97365-5258 United States
AU: Fox, C G
EM: Christopher.G.Fox@noaa.gov
AF: NOAA/National Geophysical Data Center, NOAA/National Geophysical Data Center 325 Broadway E/GC, Boulder, CO 80305-3328 United States
AB: Axial Seamount is an active volcano on the Juan de Fuca Ridge in the northeast Pacific Ocean. During a 1998 eruption, the center of the caldera subsided up to 3.4 m. Since that time, seafloor pressure measurements made within Axial caldera show evidence that the volcano has been re-inflating. Data from long-term bottom pressure recorders show that the rate of inflation was highest in the months immediately following the eruption (20 cm/mo) and has since declined to a steady rate of ~15 cm/yr. An independent data set was obtained by making repeated measurements at an array of seafloor benchmarks with a mobile pressure recorder from a remotely operated vehicle each year since 2000. These data, which are not susceptible to pressure gauge drift ambiguities that affect the long-term bottom pressure recorders, also indicate uplift is occurring in the caldera at a rate up to 19 ñ 3.6 cm/yr relative to a point outside the caldera. These observations suggest that the center of the caldera has re-inflated about 1.4 m (or about 40%) since the 1998 eruption, assuming uplift has been continuous since the 1998 eruption. This translates to a change in the volume of the magma reservoir of 85 x 106 m3 (assuming a spherical reservoir), or an average magma supply rate of 13 x 106 m3/yr. For comparison, this is 4-7 times less than long-term magma supply rates calculated at Kilauea Volcano, Hawaii. The rate of inflation at Axial Seamount suggests a recurrence interval of 16 ñ 2 years between eruptions, assuming that it will be ready to erupt again when it has re-inflated to 1998 levels.
DE: 8419 Eruption monitoring (7280)
DE: 8434 Magma migration
DE: 8494 Instruments and techniques
DE: 3094 Instruments and techniques
DE: 1294 Instruments and techniques
SC: Geodesy [G]
MN: 2004 AGU Fall Meeting