In seismic refraction shooting, a method in which a spread of geophones is used at increased offset for repeated shots at the same location. This is equivalent to using many spreads of geophones for a single shot. In seismic-reflection surveys it is used to provide information about root-mean-square velocities and depths to reflectors using the t2− x2 method. See also electrical sounding.
Subjects: Earth Sciences and Geography.