1. n. 
Seismic data whose energy source is a truck-mounted device called a vibrator that uses a vibrating plate to generate waves of seismic energy; also known as Vibroseis data (Vibroseis is a mark of Conoco). The frequency and duration of the energy can be controlled and varied according to the terrain and type of seismic data desired. The vibrator typically emits a linear "sweep" of at least seven seconds, beginning with high frequencies and decreasing with time ("downsweeping") or going from low to high frequency ("upsweeping"). The frequency can also be changed in a nonlinear manner, such that certain frequencies are emitted longer than others. The resulting source wavelet is not impulsive. Vibrators are employed in land acquisition in areas where explosive sources cannot be used, and more than one vibrator can be used simultaneously to improve data quality.