We have developed IASP91 shear wave propagation path correction (PPC) surfaces for use
with the EvLoc [Bratt and Bache, 1988; Nagy, 1996] location algorithm. Using the shear wave
data set from Figure 2 (EDR and LANL Regional databases), PPCs were constructed from
travel time residuals for events that met the following:
Figure 3 - Events with S phases which met the criteria for generating shear wave PPC surfaces.