HR: 09:15h
AN: V41B-06    [Abstracts]
TI: Seismoacoustic signatures of fluid oscillations in the volcanic plumbing system and eruption column
AU: Matoza, R S
EM: rmatoza@ucsd.edu
AF: Laboratory for Atmospheric Acoustics, IGPP 0225 Scripps Institution of Oceanography UC San Diego, La Jolla, CA 92093-0225, United States
AU: * Garces, M A
EM: milton@isla.hawaii.edu
AF: Infrasound Laboratory, University of Hawaii at Manoa, United States
AU: Chouet, B A
EM: chouet@usgs.gov
AF: US Geological Survey, Menlo Park, United States
AU: D'Auria, L
EM: dauria@ov.ingv.it
AF: Osservatorio Vesuviano, Napoli, Italy
AU: Hedlin, M A
EM: hedlin@ucsd.edu
AF: Laboratory for Atmospheric Acoustics, IGPP 0225 Scripps Institution of Oceanography UC San Diego, La Jolla, CA 92093-0225, United States
AU: Bass, H
EM: pabass@olemiss.edu
AF: National Center for Physical Acoustics, University of Mississippi, United States
AB: Portable arrays of broadband infrasound sensors collocated with broadband seismometers near Mount St. Helens (MSH), USA, and Tungurahua, Ecuador, have recorded many signals attributed to subsurface fluid oscillations, and strong signals associated with violent degassing. At MSH, long period (LP) seismic events modeled by a pressure transient in a subsurface resonant steam-filled crack, intermittently generate impulsive infrasonic pressure signals, while two dominantly phreatic eruptions were accompanied by strong infrasonic jet noises, and notably different seismicity. Tungurahua has produced countless explosions, LPs, gliding harmonic tremor, and jet noise lasting for several days at a time, indicative of alternating styles of degassing. We summarize the observations and then present preliminary numerical investigations of the coupling mechanism between seismic and acoustic LP events at MSH using a 3D finite difference representation of the elastodynamic and acoustic wave equations, including the effects of topography and wind. We also investigate the hypothesis that infrasonic signals observed during moderate to large eruptions at both volcanoes are generated by the same physical mechanisms underlying the generation of sonic jet noise, such as from the jet engines of flight vehicles.
DE: 8414 Eruption mechanisms and flow emplacement
DE: 8419 Volcano monitoring (7280)
DE: 8428 Explosive volcanism
DE: 8430 Volcanic gases
DE: 8434 Magma migration and fragmentation
SC: Volcanology, Geochemistry, and Petrology [V]
MN: 2007 Joint Assembly