T-WAVE GENERATION MECHANISMS

• Main Authors: Johnson, Rockne H., Norris, Roger A.
• Other Authors: HAWAII INST OF GEOPHYSICS HONOLULU
• Format: Text
• Language: English
• Published: 1970
• Subjects: Seismology; *SEISMIC WAVES; *PACIFIC OCEAN; PROPAGATION; MEASUREMENT; HIGH FREQUENCY; HYDROPHONES; SPECTRUM SIGNATURES; OCEAN BOTTOM TOPOGRAPHY; EPICENTERS; INTENSITY; REFLECTION; SURFACE PROPERTIES; *EAST PACIFIC RISE; SONAGRAMS; SPECTRUM ANALYSIS; T WAVES; Pacific; Subarctic
• Online Access: http://www.dtic.mil/docs/citations/AD0708695; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=AD0708695

The transformation of earthquake body waves to T waves is as efficient at deep slopes as at slopes which transect the sofar axis. Moreover, spectral studies of T phase signatures have shown no basis for distinguishing between the two cases. As simple downslope propagation is inadequate to explain the production of T waves at deep slopes, that process is relegated a minor role in favor of scattering from the sea floor as the dominant mechanism. A slope in the direction of propagation insures that once energy is scattered in that direction the probability of its being unfavorably rescattered upon successive approaches to the sea floor will be less. Scattering near the sea surface is detectable in the absence of bottom-scattered T waves. Such abyssally generated T waves display a distinctly higher frequency spectrum when originating in subarctic regions than when originating in lower latitudes. This difference is ascribed to downward ducting of higher frequency energy from the subarctic surface channel.