Home – Home – Jornals – Russian Geology and Geophysics 2006 number 5

A model composed of silicate sand, crushed granite, and cement was subjected to biaxial compression, and the resulting deformations have been described. During the experiment lasting for several months, with a quasi-static level of applied stresses, water was repeatedly injected into the model. It has been established that when the volume of water injected into a zone of active fractures is small as compared with the volume of the model, the acoustic emission drastically increases. The shape of seismograms and curves of repeatedness of the acoustic signals recorded before and after water injection do not differ significantly, which implies that the effect is of trigger nature. The time succession of injection-caused acoustic events is qualitatively similar to the swarm and, in some case, aftershock activity of earthquakes. Hence, this factor may have an effect on seismicity. Different types of time succession of induced acoustic activity are described by an equation known from the kinetic theory of strength provided that the parameters of activation energy and working stresses depend on time.