- Ground-motion model is:
_{0}is correlation radius of source function (or coherence size of source) (which can be approximated by C_{s}T∕2, where C_{s}is shear wave velocity), h is depth of sedimentary deposits beneath recording station and H is focal depth. - Response parameter is pseudo-velocity for 0, 2, 5, 10 and 20% damping.
- Screen data to minimize possible bias due to uneven distribution of data among different magnitude ranges and site conditions or from excessive contribution to database from several abundantly recorded earthquakes.
- Include term, b
_{4}(T)Δ∕100, but insignificant for most periods so remove. - Equation only applies for M
_{min}≤ M ≤ M_{max}, where M_{min}= -b_{1}(T)∕(2b_{6}(T)) and M_{max}= -(1 + b_{1}(T))∕(2b_{6}(T)). For M ≤ M_{min}use M_{min}everywhere except first term. For M ≥ M_{max}use M_{max}everywhere. - Use method of Trifunac (1980) for uncertainties.
- Note estimates should only be used where signal to noise ratio (based on estimated digitisation noise) not much less than unity or slope in log-log scale is not significantly greater than -1.
- Also fit data to log
_{10}PSV(T) = M +Att(Δ,M,T)+b_{1}(T)M +b_{2}(T)s+b_{3}(T)v +b_{5}(T)+b_{6}(T)M^{2}(where s = 0 for sediment sites, 1 for intermediate sites and 2 for basement rock sites) because depth of sediment not always known.