Nonlinear Attenuation Effects Outside the Zone of Macroscopic Failure
- Steven R. Taylor,
- Howard J. Patton and
- Paul G. Richards
Published Online: 18 MAR 2013
Copyright 1991 by the American Geophysical Union.
Explosion Source Phenomenology
How to Cite
Bonner, B. P. and Wanamaker, B. J. (1991) Nonlinear Attenuation Effects Outside the Zone of Macroscopic Failure, in Explosion Source Phenomenology (eds S. R. Taylor, H. J. Patton and P. G. Richards), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM065p0091
- Published Online: 18 MAR 2013
- Published Print: 1 JAN 1991
Print ISBN: 9780875900315
Online ISBN: 9781118663820
- Underground nuclear explosions—Detection—Congresses;
Laboratory evidence unambiguously shows that the mechanical response of rock at low confining pressure is nonlinear, meaning that attenuation is strain-amplitude-dependent, for strains between ∼10−6 and those sufficient to cause permanent damage, 10−3 to 10−2. We compare the magnitude of nonlinear attenuation for soils, microscopically cracked granite, and macroscopically fractured granite. A compilation of data for attenuation in soils from the civil engineering literature documents the strong nonlinear response in these materials over the strain range 10−6 to 10−3. Nonlinear soil response would be most important in near surface layers. We show direct evidence that fatigue microcracking resulting from high-frequency and ultrasonic measurement techniques may lead to systematic overestimates of nonlinear attenuation. New data for attenuation due to sliding on a single macrofracture in granite shows that large attenuation (up to Q−1 = 0.1) can occur at strains of 5 × 10−4 at low normal stress. Measurable nonlinear response attributable to the fracture persists to strains near 10−6 and to normal stresses corresponding to overburden pressures at typical burial depths for underground explosions.