Seismic · Exploration
Vibroseis Truck
A heavy truck that lowers a steel baseplate onto the ground and shakes it in a controlled sweep, sending sound waves into the earth.
What it does
The frequency changes continuously during each sweep. The long recorded signal is then correlated with the known sweep so it looks like the record of a single short shot. Several vibrators often work together on one source point.
Basics
| Sweep length | Usually 7 to 35 s |
| Frequency | About 12 to 60 Hz in a typical sweep |
| Needs | Relatively flat ground, no shot holes |
| Processing | Cross correlation with the sweep |
Common failures
- Poor coupling between the baseplate and soft ground, which weakens and distorts the signal
Troubleshooting
- Symptom
- Noisy or weak records at some source points
- Likely cause
- Soft or uneven ground under the baseplate
- What to check
- Move the point, add sweeps or vibrators, or switch to shot holes there