A note on pulse broadening and anelastic attenuation in near-surface rocks

A pulse rise-time method has been used to study pulse broadening on seismograms generated by a weight drop source at distances up to 600 m. Both source and receiver were placed on glacial overburden overlying a gneiss-monzonite rock body. One of two data sets showed a significant increase in pulse rise time, τ, as a function of travel time, T. This increase, if due to anelastic attenuation in the uppermost part of the rock body, implies a Q value of 243 ± 53, assuming a linear relationship between τ and T. The data were not capable of discriminating between the models of pulse broadening of Gladwin and Stacey (τ ∞ T) and Ricker ($\text{τ ∞ T}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$).