HR: 0800h
AN: NG41A-0140    [Abstracts]
TI: Modeling of Active Monitoring with Harmonic Vibrational Signals
AU: * Kovalevsky, V
EM: kovalevsky@sscc.ru
AF: Institute of Computational Mathematics and Mathematical Geophysics SB RAS, pr.akad.Lavrentieva, 6, Novosibirsk, 630090, Russian Federation
AB: The active seismic monitoring is based on the sounding of the geological medium by the seismic waves from controllable vibrational sources. Vibrational sources can generate stationary harmonic wave fields, which can be effectively used to monitor the variability of the medium in time. A stationary harmonic wave field is formed in the medium due to the long time radiation by the vibrator of a harmonic signal with constant characteristics, such as frequency, amplitude, and phase. The direct problem of modeling of active monitoring with harmonic vibrational signals is solved. It is determined the change in the characteristics of the stationary wave field recorded at the surface cause by the changes in the density and velocity of seismic waves in some inner area of the medium. The results of a mathematical modeling of vibroseismic monitoring of changes in the elastic characteristics in the interior Earth's crust zone in the approximation of the wave equation and of a model of the Earth's crust-mantle system in the form of a layer at a half-space with different velocity values of elastic waves are presented. It is assumed that the vibrational source is a point and harmonic one, with a constant oscillation frequency, and that the zone of changes of the characteristics in the medium is spherical. The wave field in the medium is calculated in the ray approximation. Wave field variations in the medium and at the free surface are determined for the case of small velocity changes in the spherical region by calculating the beam pattern of a fictitious 3D source in diffraction approach. As a result of the modeling the estimation of sensitivity of active monitoring method with harmonic vibrational signals is done.
DE: 7219 Seismic monitoring and test-ban treaty verification
DE: 7223 Earthquake interaction, forecasting, and prediction (1217, 1242)
DE: 7290 Computational seismology
DE: 7294 Seismic instruments and networks (0935, 3025)
SC: Nonlinear Geophysics [NG]
MN: 2007 Fall Meeting