GEOL463
VibroSeis source
Rather than
using explosions, acoustic energy can be distributed in time by using a hydraulic vibrator device
nUsually mounted on a heavy truck
nSmall borehole vibrators, portable vibrators, and
>100-ton stationary
vibrators also exist.
The signal
consists of a quasi-monochromatic “sweep” of gradually changing frequency, covering ~20-150 Hz
To produce
stronger signal, vibrators are able to operate synchronously (vibrate in-phase) in a group
The signal
sent into the ground is carefully recorded and afterwards “correlated” with the recordings to produce
an equivalent of impulsive
excitation