The frequency-magnitude relation of microfracturing in rock and its relation to earthquakes

TLDR

Laboratory rock deformation produces microfractures that emit elastic waves analogous to earthquakes. The study measured microfracture radiation during uniaxial and triaxial compression tests, examined how the b‑parameter varies with rock type, stress, and confining pressure, and derived the Gutenberg–Richter relation from a statistical model of rock deformation. Microfracture events obey the Gutenberg–Richter law, with the b‑parameter mainly governed by stress and higher in ductile rock sliding, illustrating the similarity between laboratory rock deformation and crustal deformation.

Abstract

abstract During the deformation of rock in laboratory experiments, small cracking events, i.e., microfractures, occur which radiate elastic waves in a manner similar to earthquakes. These radiations were detected during uniaxial and triaxial compression tests and their frequency-magnitude relation studied. They were found to obey the Gutenberg and Richter relation log N = a + b M Where N is the number of events which occurred of magnitude M, and a and b constants. The dependence of the parameter b on rock type, stress, and confining pressure was studied. It was found to depend primarily on stress, in a characteristic way. The frequency-magnitude relation for events which accompanied frictional sliding and deformation of a ductile rock was found to have a much higher b value than that observed in brittle rock. The Gutenberg and Richter formulation of the frequency-magnitude relation was derived from a statistical model of rock and crustal deformation. This analysis demonstrates the basis of similarity between rock deformation experiments in the laboratory and deformation of the crust.