Abstract
Multiple ships equipped with multichannel seismic receiving arrays and sound sources can be used in a variety of configurations to acquire wide aperture seismic reflection and refraction data. One experiment, the Expanding Spread Profile, acquires Common Midpoint data as two ships steam on opposite tracks away from the midpoint of the profile. Source-receiver separations of 100 km or greater are achieved with a maximum seismogram separation of 100 m. Source-receiver offsets are accurately measured using Raydist ranging. The density of the recorded data make it possible to transform the data acquired to the domain of intercept time and ray parameter for analysis. This experiment provides detailed velocity-depth information at a fixed geographic location for deep ctustal and subcrustal studies. In a second two-ship experiment both ships steam on the same track at a fixed separation selected to track arrivals from target horizons. By alternately firing their sound sources and recording the arrivals from both sources, the two ships can acquire Wide Angle Common Mid-point data at a constant offset. Since the offsets of interest are typically less than 30 km, range can be determined using a Miniranger type ranging unit. These data can also be interpreted in terms of vertical delay time and ray parameter along the track traversed.
Published Version
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