Seismic Source Parameters

The use of information contained on seismograms to infer the properties of an explosion source presents an interesting challenge because the seismic waves recorded on the seismograms represent only small indirect, effects of the explosion. The essential physics of the problem includes the process by which these elastic waves are generated by the explosion and also the process involved in propagating the seismic waves from the source region to the sites where the seismic data are collected. Interpretation of the seismic data in terms of source properties requires that the effects of these generation and propagation processes be taken into account. The propagation process involves linear mechanics and a variety of standard seismological methods have been developed for handling this part of the problem. The generation process presents a more difficult problem, as it involves non-linear mechanics, but semi-empirical methods have been developed for handling this part of the problem which appear to yield reasonable results. These basic properties of the seismic method are illustrated with some of the results from the NPE.