RESEARCH DIRECTED TOWARD THE USE OF LONG AND INTERMEDIATE PERIOD SEISMIC WAVES FOR THE IDENTIFICATION OF SEISMIC SOURCES
Final rept. 1 Aug 1964-31 Jul 1968
LAMONT GEOLOGICAL OBSERVATORY PALISADES NY
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In the period covered by this report, Lamont Geological Observatory has made significant advances towards the use of long and intermediate period seismic waves for the identification of seismic sources. Our increased understanding of many features of the seismogram has enhanced its utility in detecting and identifying small seismic events. The recently states principles of global tectonics have shed new light on the problems of world seismicity, source mechanisms and the location of seismic events. The structure and causes of seismic noise which limits the effectiveness of all detecting instruments are now understood so well that much of the noise can be predicted. A large network of long and intermediate period instruments has been operated, and new high sensitivity, broadband, low noise instruments have been developed which have proved especially effective for detecting small events. A study of the relative excitation of surface waves by earthquakes and explosions revealed it to be a powerful discriminant between two sources. The steady development of computer programs has permitted rapid and sophisticated analysis of both conventional and Large Aperture Seismic Array data. Thus many of the goals of this research have been attained and important progress has been made toward detecting and identifying seismic events.