Multi-channel seismic reflection survey was carried out in Tokyo Bay along 6 lines of 130km in total length by the Hydrographic Department in March 1982. For this surveytwo air guns of 500 cubic inches were used as sonic source and a 24 channel streamer cableof 1200m length were used as a receiver. Acquired data were processed by the methods of CDP stacking, time migration, depth conversion and others. Then 12-fold stack section, migrated time section and migrated depth section for each line were made after these processing. We can clearly find the geological structure beneath Tokyo Bay to about 3 kmdepth on these sections.
The geological structure beneath Tokyo Bay is summerized as follows:
1) Pre-Neogene basement rocks in the Kanto area are found at 2-3km depth in thecenter of the Bay, and more than 3.4km depth in the southern part of the Bay.
2) A fault with strike of N50-55°W is found at the northern part of the Bay, whichdisplaced the Pre-Neogene basement down to 420m on the north.
3) Neogene and Quaternary layers of 2-3km thick cover the Pre-Neogene basement. From the lower layer to the upper one, the part of maximum thickness moves from southto northeast in the Bay.
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