Home – Home – Jornals – Russian Geology and Geophysics 2001 number 7

Instant variations in velocity and attenuation of seismic waves in a friable medium subjected to dynamic loading have been studied by new experimental techniques using a powerful seismic vibrator. The half-space below the operating vibrator baseplate was scanned by high-frequency elastic waves, and the recorded fluctuations were exposed to a stroboscopic analysis. The pulses of seismic velocities and attenuation are synchronous with the external load pulses but are out of phase with the latter and with each other. Instant variations in the studied parameters depend on the magnitude and absolute rate of deformation, which always reduces elastic-wave velocities. Some weak seismic boundaries have shown a high sensitivity to the presence of dynamic disturbance in the medium.