Science Center Objects

Seismic source for marine reflection surveys

Illustration of an cylindrical instrument with clamps for mounting it and openings to see inside the cylinder.

Mini GI seismic source

Description

Seismic source for high-resolution multichannel seismic system. Pressurized air releases a pulse of acoustic energy. This pulse penetrates and bounces off of the seafloor and its subsurface at varying speeds, depending on the kind of rock, sand, mud, or discontinuous layers that it hits. Receivers listen for the return pulses and record them, generating a cross-section of the subsurface beneath the seafloor. This cross-sectional reflection reveals the shape of subsurface material including the locations of faults and buried channels that would not otherwise be visible.

Specifications

  • Manufacturer - Sercel, Inc.
  • Model – Mini GI
  • Weight – 60 lbs (27kg)
  • Dimensions - Length 588mm, Width 200mm, Volume 60 cu. In.
  • Power Requirements - Air at 2,000 psi

Operational Characteristics

  • Minimum Operational Depth - 100m
  • Maximum Operational Depth - unlimited
  • Ship’s Requirements
    • All overboarding gear rated to a SWL of 500 lbs.
    • A-frame or davit with minimum height of 10’
    • 15’ x 15’ of clear deck space
    • Deck winch with line pull of at least 500 lbs for deployment and recovery of equipment
    • Ability to line-follow and hold heading in variety of sea states at speeds of 2-4 knots

Additional Equipment required

  • Shot Controller
  • High Pressure air compressor
  • Banked air storage
  • Seismic streamer or other data acquisition system

Complementary Systems

As a seismic source, the Sercel Mini GI is most often used in pairs, coordinated by a shot controller, and towed in combination with a multichannel streamer that receives the signal.  Additional resources include a near-field hydrophone, sonobuoys, and magnetometer.