Frequency dependence of sound speed and attenuation in marine sediments

Abstract

Zhou and Zhang [J. Acoust. Soc. Am. (2005) (2006)] have reviewed diverse data for propagation in sandy sediments. Attenuation for frequencies below 1 kHz corresponds roughly to α=0.34(f/fo)2 dB/m with the reference frequency being 1 kHz. The best‐fit exponent is slightly less than 2. Their review of results for frequencies above 10 kHz suggests a substantially different frequency dependence. They considered two explicit models, the Biot model as parametrized and extended by Stoll and the BICSQS model of Chotiros and Isakson [J. Acoust. Soc. Am. (2004)]. In either case the fit of parameters to match sound speed dispersion resulted in an unsatisfactory fit of attenuation versus frequency, and conversely. The present paper reexamines this and contends that, while Biot’s formulation is intrinsically correct at low frequencies, Stoll’s parametrization is noncausal: Chotiros’ model more nearly captures the correct physics in that it is intrinsically causal and includes relaxation processes. A considered extensi...