RESEARCH DIRECTED TOWARD THE USE OF LONG-AND INTERMEDIATE-PERIOD SEISMIC WAVES FOR THE IDENTIFICATION OF SEISMIC SOURCES

Abstract : Research carried out during the period of this report provided many interesting results useful to the field of nuclear detection as well as seismology in general. A study of the relative excitation of surface and body waves by nuclear explosions and earthquakes has been done for the Longshot nuclear test and 29 earthquakes in the same area as Longshot. The analyses showed that the nuclear explosions had surface wave magnitudes which were much smaller than those of earthquakes with body wave magnitudes comparable to the explosions. A frequency analysis was performed on P waves recorded at Palisades, New York, from Long shot and some Aleutian earthquakes. For periods longer than 10 seconds, the spectral amplitudes for Longshot were at least one order of magnitude smaller than those observed for two earthquakes from the same area and of the same body wave magnitude. Other topics which are covered in this report are PcP waves generated by nuclear explosions and earthquakes, analysis and application of shear coupled leaking modes, transmission and reflection of Rayleigh waves across structural boundaries, and microearthquake studies in Alaska and California. (Author)