During the Amchitka testing program, recordings were made of the near-field ground velocity for events MILROW and CANNIKIN. These records exhibited a P arrival, a feature associated with near-field pP and a developing Rayleigh wave. In this investigation, simple models were found which match the complete seismograms. They simultaneously predict the amplitude, wave shape, timing, and periodicity of both the body waves and the surface waves. Models for both the Amchitka crustal structure and the source time functions were developed. The crustal model is similar to previous models in its averge properties, so travel time constraints are still satisfied. Small modifications have been made to match the waveform data. The events on Amchitka can apparently be represented as isotropic point sources with the types of simple source time histories predicted by classical yield scaling laws. A source model for event LONGSHOT was developed on the basis of the yield scaling laws since no near-field records are available for it. The source models were tested by comparing the teleseismic body waveforms they predict with observations. Short-period P waves, long-period P waves, and long-period pS waves were considered. The short-period P waves provided the best constraint. To match them, it was necessary both to develop a model for teleseimic pP since it arrives later than the near-field model would predict and to estimate the average value of t*. The MILROW and CANNIKIN teleseismic short-period P waves indicate that the average effective tα* for teleseismic ray paths from Amchitka is 0.9 s. The scatter about this value, however, is very substantial. The accuracy of the scaling laws was tested by comparing synthetics for LONGSHOT to teleseismic observations. The predicted amplitudes and wave shapes fall within the scatter in the observations, though again this scatter is substantial. |