Translations:Dictionary:Spread/3/en

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FIG. F-1. Fan shooting. Detectors are located roughly on the arc of a circle centered at the source point in different directions. Expected arrival times are determined from a normal traveltime curve (versus distance) where no local high-velocity body is present. An early arrival (lead) with respect to the normal indicates that part of the travelpath is at an abnormally high velocity, signifying the presence of a local high-velocity body such as a salt dome. This method was used in early seismic exploration to locate salt domes within the thick low-velocity Gulf Coast sediments. (From Nettleton, 1940.)
FIG. T-4. 3-D surveying (Continued)

2. The layout of electrodes or antennas in resistivity or electro-magnetic surveying. See array (electrical).