OCEAN-BOTTOM SEISMOMETER DATA COLLECTION AND ANALYSIS
TEXAS INSTRUMENTS INC DALLAS
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Ocean-bottom data from three independent geographical locations in the Pacific Ocean has been studied for consideration of means of detecting and identification of underground or underwater nuclear explosions. Signal-to-noise ratios on the ocean bottom are generally inferior to those at a land control station by 0 to -10 db in two of the three areas. The superior ocean-bottom S N ratios in the Hawaii area are due principally to a noisy land site. The study reveals no consistent differences in phase development between the ocean bottom and land other than effects associated with the free surface and the late arriving T phase. For near regional and local events, the ocean-bottom seismogram often shows greater high frequency energy content than on land. Ocean-bottom magnification of signal energy by as much as 20 db is consistently observed for teleseisms and occasionally for near regional and local events. Ambient noise levels on the ocean bottom are greater than at a land control station by about 20 db at the low frequencies in all three areas. The difference decreases with increasing frequency.
- Physical and Dynamic Oceanography