HR: 0830h
AN: S11E-0337    [PDF]
TI: Volcano monitoring using continuous data
AU: * Snieder, R
EM: rsnieder@mines.edu
AF: Dept. of Geophysics and Center for Wave Phenomena, Colorado School of Mines 1500 Illinois Str. Golden CO 80401-1887, Golden, CO 80401 United States
AU: Hagerty, M
EM: m.hagerty@gns.cri.nz
AF: Inst. Geological Nuclear Science, Private Bag 2000, Wairake, 0000 New Zealand
AB: Mt. Arenal is a volcano that has been heavily instrumented. In this study we used continuous recordings of air pressure and ground motion to monitor Mt. Arenal. The pressure record shows a sequence of distinct pulses. The time interval between these pulses changes with time. The associated ground motion resembles a superposition of overlapping exponentially decaying signals. We carried out a deconvolution of the ground motion with the pressure for a number of non-overlapping time intervals. Under the assumption that the pressure pulses are related to the excitation of the seismic waves, this should give the seismic impulse response of Mt. Arenal. The deconvolved signals obtained from the different time intervals display the typical character of coda waves with a diffusive character. Even though the waveforms are complex, they are highly reproducible. The deconvolved waves from adjacent time windows have a high correlation with a correlation coefficient of about 0.95 or more. This correlation coefficient decreases to about 0.80 for the deconvolved waveforms that are from time windows with a separation in time of about 10 minutes. On the basis of the employed data, the cause of the change in the waveforms cannot be established unambiguously. However, the de-correlation of the deconvolved waves can be explained by a change in the location of the seismic source over about 60 meters during a 10 minute interval. The reproducible character of the deconvolved signals and their gradual and systematic change with time open up the possibility of passive volcano monitoring using coda wave interferometry [Snieder, R., A. Gret, H. Douma, and J. Scales, Coda wave interferometry for estimating nonlinear behavior in seismic velocity, Science, 295, 2253-2255, 2002].
DE: 1734 Seismology
DE: 8400 VOLCANOLOGY
SC: Seismology [S]
MN: 2003 Fall Meeting