HR: 15:25h
AN: V13D-08    [Abstracts]
TI: Analogue Experiments on the Generation of Flow-Induced Tremor
AU: * Rust, A C
EM: arust@eos.ubc.ca
AF: University of British Columbia, Dept. Earth & Ocean Sciences 6339 Stores Road, Vancouver, BC V6T1Z4 Canada
AU: Balmforth, N J
EM: njb@math.ubc.ca
AF: University of British Columbia, Dept. Earth & Ocean Sciences 6339 Stores Road, Vancouver, BC V6T1Z4 Canada
AB: We explore the generation and properties of vibrations induced by fluid flow through a crack in an elastic medium by sending either air or water through a fracture in concentrated gelatin. The ambient stress field is varied by changing the orientation of both the crack and the fluid flow direction with respect to the gravitational force. Stresses near the crack walls are examined qualitatively by making use of the photoelastic properties of gelatin. Motions of the crack walls are imaged with high speed photography and acoustic energy is recorded with a microphone. Preliminary results indicate that the system is non-linear and that the ambient stress field affects both the onset of instabilities and the power spectrum of the acoustic signals. Fluid pressure opens the crack, and flow-induced oscillations of the walls are generated if the fluid flows fast enough. These vibrations generate relatively low frequency non-linear acoustic signals, which under some experimental conditions are punctuated by short duration higher frequency sounds produced by crack walls clapping together. The results of the experiments are compared with predictions from theoretical linear stability analysis, numerical simulations, and observations of volcanic tremor.
DE: 8419 Eruption monitoring (7280)
DE: 7280 Volcano seismology (8419)
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2004 AGU Fall Meeting