Ch. 4— Technologies for Exploring the Exclusive Economic Zone • 135 



Figure 4-10.— Seismic Record Willi Interpretation 



Sea-surface 



Academic and industry researchers interpret seismic records to help them determine geological 

 structure and stratigraphy below the seabed. 



SOURCE: U.S. Geological Survey. 



tions, and with geochemical sampling of bottom 

 sediments and of the water column, etc., for the 

 highest quality interpretations. 



Advances in reflection seismology have been 

 made more or less continuously during the approx- 

 imately 60 years since its invention.*' Recent tech- 

 nological innovations have been the development 

 of three-dimensional (3-D) seismic surveying and 

 interactive computer software for assisting interpre- 

 tation of the mountains of 3-D data generated. To 

 acquire enough data for 3-D work, survey lines are 

 set very close together, about 25 to 100 meters 

 apart. Data for the gaps between lines then can 

 be interpolated. The efficiency of data acquisition 

 can be increased by towing two separate streamers 



"C.H. Savit, "The Accelerating Pace of Geophysical Technology," 

 Oceans 84 Conference Record, Sponsored by Marine Technology So- 

 ciety and lEEEE Ocean Engineering Society, Sept. 10-12, 1984, 

 (Washington, D.C.: Marine Technology Society, 1984), pp. 87-89. 



(and technical advances will soon enable two lines 

 of profile to be acquired from each of two separate 

 cables).*^ 



Interactive programs allow the viewer to look at 

 consecutive cross-sections of a 3-D seismic profile 

 or at any part of it in horizontal display. Thus, if 

 desired, the computer can strip away everything 

 but the layer under study and look at this layer at 

 any angle. Moreover, the surveyed block can be 

 cut along a fault line, and one side can be slid along 

 the other until a match is made. Interpretation of 

 data can be accomplished much faster than on pa- 

 per. Such systems are expensive. While the cost of 

 acquiring and processing 20 kilometers of two- 

 dimensional seismic data may be from $500 to 

 $2,000 per kilometer, a 3-D high-density survey 



^Savit, OTA Workshop, June 10, 1986. 



