Attenuation of seismic waves in dry and saturated rocks; I, Laboratory measurements

The attenuation of compressional (P) and shear (S) waves in dry, saturated, and frozen rocks is measured in the laboratory at ultrasonic frequencies. A pulse transmission technique and spectral ratios are used to determine attenuation coefficients and quality factor (Q) values relative to a reference sample with very low attenuation. In the frequency range of about 0.1-1.0 MHz, the attenuation coefficient is linearly proportional to frequency (constant Q) both for P- and S-waves. In dry rocks, Q p of compressional waves is slightly smaller than Q s of shear waves. In brine and water-saturated rocks, Q p is larger than Q s . Attenuation decreases substantially (Q values increase) with increasing differential pressure for both P- and S-waves.