HR: 15:10h
AN: V13D-07    [Abstracts]
TI: Dynamics of Gas-Rock Interaction at Erupting Volcanoes
AU: * Lees, J M
EM: jonathan.lees@unc.edu
AF: University of North Carolina, Campus Box 3315, Chapel Hill, NC 27599-3315 United States
AU: Ruiz, M
EM: mruiz@email.unc.edu
AF: University of North Carolina, Campus Box 3315, Chapel Hill, NC 27599-3315 United States
AB: Multi-parameter waveform observations of volcanic activity can provide new and detailed information on the volcano-atmosphere interface and illuminate the physical processes governing the interaction of thermal fluids escaping the earth. Recent investigations at several volcanoes utilize seismic, acoustic and visual observations to constrain the evolution of explosive activity. We present evidence of non-linear explosive chugging activity at Karymsky Volcano, Russia, and Sangay Volcano, Ecuador, and present a model showing how oscillatory behavior can be modeled by a choked vent. New, high quality measurements of acoustic arrival times (at Sangay) and detailed error analysis shows a strong correlation of acoustic amplitude with time between oscillatory pulses at two active volcanoes. Time-domain analysis of numerous episodes of oscillatory tremor shows a statistically significant positive correlation between amplitudes and interval times, indicating a feed back system near the vent. Specifically, we can show that, in general, larger pulses in the oscillatory sequence produce longer the time intervals before the next pulse. In particular, we show that activity can be modeled as choked fluid flow through narrow conduits near surface vents, analogous to a common kitchen pressure cooker.
DE: 8414 Eruption mechanisms
DE: 8419 Eruption monitoring (7280)
DE: 7280 Volcano seismology (8419)
DE: 7215 Earthquake parameters
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2004 AGU Fall Meeting