Inversion for Source Parameters of Underground Nuclear Explosions with Implications for Yield Estimation.

The first part of this report presents a method for simultaneous inversion of near-field explosion waveforms for parameters of the source and structure. The inversion automatically provides information on the trade offs between parameters and error analyses of the resultant models. The source may be parameterized by any of several effective source functions. The structure is parameterized as a layered stack of gradients defined by the velocity at the top of the layer, the velocity gradient within the layer and the depth to the top of the layer. The gradient model is then discretized into homogeneous plane layers, with the layer thickness defined as the wavelength of the predominant period in the data, and synthetics are computed using asymptotic generalized ray theory. For each observed waveform, the residuals consist of the normalized cross-correlation coefficient between the data and synthetics, the difference in normalization factors and the time lag to the peak of cross-correlation. The second part of the report addresses the implications of choosing a particular representation of the RDP on the determination of teleseismic attenuation. This time-domain analysis is based on a near-field to far-field amplitude comparison. The near-field amplitude information is contained in the parameters of the explosion source model assuming amplitude information is contained in the parameters of the explosion source model assuming either the Mueller-Murphy or Helmberger-Hadley representations.