Nerseov et al. (1969) found that the travel-time ratio of shear and compressional waves, ξ = ts/tp varies prior to the occurrence of earthquakes in the Garm region, USSR. Laboratory results indicate that the decrease of ξ can result from dilatancy of rocks around the focal zone. The subsequent increase of ξ, which terminates with an earthquake, can be caused by the flow of ground water into the dilated zone. The increasing pore pressure weakens the rock and leads to the observed failure.

First Page Preview

First page PDF preview
You do not have access to this content, please speak to your institutional administrator if you feel you should have access.