ABSTRACT
The seismic displacement discontinuity model supposes that displacements are locally discontinuous in the plane of a fracture. Normal and shear displacements may be coupled and viscous loss may occur in addition. The consequences of these assumptions on theoretically predicted wavefields are many, including frequency dependent amplitude and velocity changes in transmitted and reflected waves, generations of converted waves and waves trapped as interface waves on the fracture and guided waves between parallel fractures. A number of these characteristics have been observed in laboratory experiments on artificial and natural fractures. Field observations are more limited but have provided evidence of the validity of the model at practical engineering scales.
