A spherical focal model is considered in which the release of the shear energy at the time of rupture sets up a laminar displacement field. Based on some geodetic observations, the field is assumed to decrease gradually as the distance from the focal point increases. This assumption allows the fault plane to be of finite extent.
The concept of static elasticity is applied to evaluate the fraction of stored shear energy which is released with the occurrence of an earthquake. Comparison of the distribution of the strain energy density in the focal region before and after rupture leads to some explanation about the partition of energy in that region.
The application of the model to three shallow earthquakes in the western United States yields energies comparable to those given previously.