Attenuation of P-Waves by Wave-Induced Fluid Flow.

Pride, S. R. ; Berryman, J. G.

Technical Information Center Oak Ridge Tennessee

关键词: Rocks;    Comparisons;    Numerical analysis;    Frequency bands;    Analytical expressions;   

RP-ID  :  DE200515013446

学科分类：工程和技术（综合）

美国|英语

来源: National Technical Reports Library

【 摘 要 】

Analytical expressions for three P-wave attenuation mechanisms in rocks are given and numerically compared. The mechanisms are: (1) Biot loss, in which flow occurs at the scale of the wavelength between the peaks and troughs of a P wave; (2) squirt loss, in which flow occurs at the grain scale between microcracks the grains and the adjacent pores; and (3) mesoscopic loss, in which flow occurs at intermediate scales between the various lithological bodies that are present in an averaging volume of earth material. Each mechanism is of importance over different frequency bands. Typically, Biot loss is only important at the highest of ultrasonic frequencies (> 1 MHz), squirt-loss (when it occurs) is important in the range of 10 kHz to 1 MHz, while mesoscale loss dominates at the lower frequencies (<10 kHz) employed in seismology.