The first research update describes a discrimination experiment. Digital short and long period body and surface wave data for Eurasian events recorded at a global network of stations are being provided for event discrimination. Efforts to date have focused on application of the VFMVariable Frequency Magnitude discriminant to the short period P waves at eight stations. Twenty-eight events were analyzed and tentative identification made. The second project is entitled Surface Wave Solution for the Elastic Equivalent of a Complex Axisymmetric Source. In our last quarterly report we presented the mathematical development of a method for linking finite difference numerical source calculations with analytical technical for propagating body waves in layered elastic media. In this report the theory is extended to include the propagation of Rayleigh waves. The third project is entitled Source Calculations. Our one-dimensional constitutive models for the numerical simulation of the explosion source were reviewed to ensure their compatibility with our two-dimensional finite difference programs. Three important improvements to the models were made. The new models and their effect on source calculations for PILEDRIVER, SALMON and Rainier Mesa tuff are described.