Sources

1
Seismic data acquisitionLand equipment

• Sources
• Dynamite
• Impulsive
• generates a Ricker wavelet
• Vibroseis
• Non-impulsive
• Long sweep
• Autocorrelated to produce a Klauder wavelet

2
Seismic data acquisitionLand equipment

• Detectors
• Geophone
• coil hanging inside cylindrical magnet by spring
• Magnet moves with ground.
• Coil stays fixed by spring inertia.
• electric current produced
• measure ground velocity
• important to plant them firmly and vertically

3
Seismic data acquisitionMarine equipment

• Sources
• Air gun
• blows high-pressure air into water
• produces bubble effect
• most commonly used
• Detectors
• Hydrophone
• made of a piezoelectric material
• generates voltage when stressed
• measure fluid acceleration
• independent of wave direction
• Depth is 10-15 m under water.
• mounted in a streamer ( 6 km long)

4
Seismic data acquisitionRecording

1. Signal from detectors is digitized and amplified.
2. Filters may be applied to remove unwanted
   frequencies.
3. Traces are displayed for quality control.
4. Data is recorded and stored in tapes for later
   retrieval and processing.

5
Seismic data acquisitionRecording
Earths surface
Filter
R
S
A/D Converter
Amplifier
Trace display
Recording
Subsurface reflector
Tape storage