Frictional attenuation: An inherent amplitude dependence

Frictional sliding on crack surfaces and grain boundaries is examined as a mechanism of wave attenuation. In contrast to previous work based on idealized elliptic crack models a general description of internal surfaces is considered which allows for irregularities and partially closed cracks. This leads to Q−1 that increases with strain amplitude. Such an amplitude dependence is often observed in large‐strain laboratory measurements. This suggests that under in situ (small strain) conditions, frictional attenuation becomes secondary to linear loss mechanisms, either disappearing or becoming masked.