High-frequency acoustic emission effect

Complex monitoring of acoustic emission (AE) in the sound frequency range has been carried out in the Kamchatka peninsular since 1999. In the course of the investigation, the existence of acoustic emission effect in sedimentary rocks was detected. It consists in the increase of geoacoustic radiation intensity in the frequency range from hundreds of hertz to the first tens of kilohertz during the growth of rock mass deformation rate. This effect was stably observed at several spaced stations and appears the most vividly at the final stage of earthquake preparation. During the acoustic emission effect, clear anisotropy of geoacoustic radiation directivity occurs which is determined by the source orientation of acoustic oscillations in the stress field of near surface sedimentary rocks.