. Collected reprints / Atlantic Oceanographic and Meteorological Laboratories [and] Pacific Oceanographic Laboratories. Oceanography ifk-^^U * â .i'.rf. '.«!,-'⺠-- -.â¢Â£'.'.\1''1L *.».**£ â¢-â^./ .'â¢Â»" uoei- Figure 23. A high resolution, shallow penetration ( kilo- meters) seismic reflection profile shows sediment-filled river channels cut in bedrock beneath the surface of a continental shelf. Penetration by different systems varies between about 1 meter and 10 kilometers beneath the ocean bottom. Penetration is primarily deter- mined by the amount of energy trans
. Collected reprints / Atlantic Oceanographic and Meteorological Laboratories [and] Pacific Oceanographic Laboratories. Oceanography ifk-^^U * â .i'.rf. '.«!,-'⺠-- -.â¢Â£'.'.\1''1L *.».**£ â¢-â^./ .'â¢Â»" uoei- Figure 23. A high resolution, shallow penetration ( kilo- meters) seismic reflection profile shows sediment-filled river channels cut in bedrock beneath the surface of a continental shelf. Penetration by different systems varies between about 1 meter and 10 kilometers beneath the ocean bottom. Penetration is primarily deter- mined by the amount of energy transmitted by the sound source in the low frequency range (less than 100 Hertz, , cycles per second) because low frequencies of sound undergo less absorption in travel through sediment and rock layers than higher frequencies. The resolu- tion of different seismic reflection systems varies between about one meter and hundreds meters. Resolution is related to the duration, peak frequency, and frequency content (bandwidth) of the acoustic signal transmitted. In general, the shorter the duration, or the higher the peak frequency, or the wider the bandwidth, the thinner the layer that can be resolved (Brillouin, 1956). Shortening of the signal duration limits the amount of energy transmitted resulting in decreased penetra- tion. Raising the peak frequency (greater than 100 Hertz) also limits the penetration by increasing absorption losses. Widening the signal bandwidth does not restrict the amount of energy that can be transmitted and is being developed as the most promising direction to achieve relatively deep penetration with high resolution. The state-of-the-art forces the user to choose between systems which achieve either high resolution or deep penetration. The choice depends on whether the objective is to find a relatively thin deposit in the upper several hundred meters sub-bottom (fig. 13) or a more 776. Please note that these images are extracted fr
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