Rates of slip along major fault zones have been computed from the sums of moments based on seismicity. These rates are compared with rates of slip estimated from geologic, geodetic, and geophysical evidence and found in approximate agreement. Accurate summation of moment combined with geodetic measurements of regional deformation and creep along faults can be combined to estimate earthquake potential.
The state of stress in the earth's crust can be estimated from the spectra of seismic waves. In California there are indications of regional variations in stress. An upper limit to the absolute stress along the San Andreas fault can be estimated from the lack of a heat flow anomaly associated with fault friction. Depending on whether most of the slippage occurs as creep or rapid faulting during large earthquakes, the upper limit varies from about 100 to 250 bars if a long-term average rate of slip of 5 cm/year is assumed