The relationship between Q E −1 and dispersion in extensional modulus, E

We have measured the extensional modulus (ratio of stress to strain, E ) and the fractional energy loss per radian ( Q E ‐1 ) as functions of frequency in cylindrical samples of two solids: a room‐dry sandstone (Berea) and an acrylic plastic (Lucite). In the seismic frequency range (0.1–100 Hz), Q E ‐1 for the sandstone is constant, while the sandstone modulus follows a power law of frequency,   allowing Q E ‐1 to be independently estimated from the slope of log E versus log f . In the same frequency range, Q E ‐1 for the acrylic plastic is not constant but exhibits a slight relaxation peak centered about 2 Hz. In this case Q E ‐1 can be estimated from the derivative, d log E / d log f , i.e., the above power law appears to hold independently at each point in the frequency domain even when Q E ‐1 is varying.