Seismic Acquisition glossary

Clear, one-line definitions of the Seismic Acquisition terms used across the OgbonLab textbooks. Each entry links to the interactive sections where the idea is taught.

accelerometer

A seismic sensor (often MEMS-based) that records ground particle acceleration directly, with broader bandwidth and flatter low-frequency response than a geophone.

See: MEMS accelerometers

air gun

A marine seismic source that releases a high-pressure air bubble underwater, producing a broadband acoustic pulse used to image the subsurface.

aperture

The maximum source-receiver offset (or migration distance) used to image a target; must be large enough to capture steeply dipping reflections.

See: Migration aperture & design rules

azimuth

The compass direction from source to receiver, measured clockwise from north; wide-azimuth surveys sample many directions per midpoint.

See: Fold, offset, azimuth statistics, Survey design sanity: fold, offset, azimuth

bin

A small rectangular cell on the surface grid; traces falling in the same bin (sharing a CMP) are stacked to form one output trace.

bin size

The dimensions of a CMP bin; smaller bins improve lateral resolution but reduce fold per bin and require denser source/receiver spacing.

See: Bin size & dip aliasing

cmp

Common midpoint: the surface location halfway between a given source and receiver, used to bin traces that sample the same subsurface point.

common-midpoint

The CMP method groups traces whose source-receiver midpoints coincide, so that after NMO correction they image the same subsurface reflection point.

crossline direction

The axis perpendicular to the inline (cable) direction in a 3D survey; the bin spacing along this axis is set by source-line separation.

dynamite

An impulsive land seismic source using explosive charges detonated in shallow boreholes to generate broadband elastic energy.

See: Shot-hole dynamite deployment, Dynamite: charge, depth, coupling

far offset

The longest source-receiver distance in a gather; carries the largest moveout and the strongest AVO signal but also the most stretch and noise.

fold

The number of independent source-receiver traces contributing to a given CMP bin; higher fold improves signal-to-noise after stacking.

fold map

A plan-view image of the number of traces summed in each CMP bin; reveals coverage gaps and survey edge effects.

geophone

A land-based seismic sensor that converts ground particle velocity into an electrical voltage, typically via a moving coil suspended in a magnetic field.

See: Geophones: coil-magnet physics

hydrophone

A pressure-sensitive marine sensor (piezoelectric) that records acoustic pressure variations in water from a passing seismic wavefield.

See: Hydrophones and pressure sensing

marine streamer

A long towed cable carrying hydrophone groups (and often birds and tail buoys) behind a vessel to record marine seismic reflections.

near offset

The shortest source-receiver distance in a gather; carries near-normal-incidence reflections useful for stacking and shallow imaging.

obn

Ocean-bottom node: an autonomous 4-component (3-axis geophone + hydrophone) recording unit placed on the seafloor for high-fidelity wide-azimuth marine seismic.

ocean-bottom nodes

Autonomous seafloor sensor packages combining 3-component geophones with a hydrophone, deployed in grids for full-azimuth marine seismic recording.

offset

The horizontal distance between a seismic source and a receiver; controls reflection moveout, AVO behavior, and multiple discrimination.

See: Fold, offset, azimuth statistics, VSP: zero-offset, walkaway, walkaround

receiver array

A group of receivers wired in series or parallel and summed to one trace, attenuating horizontally propagating noise such as ground roll.

See: Receiver arrays and group-forming

shot

A single activation of a seismic source; also the record of all traces produced by one such activation, called a shot gather.

source

Any device that injects controlled seismic energy into the earth, such as dynamite, vibroseis trucks, air guns, or marine vibrators.

See: Source signature QC, Source-encoded FWI-PINN

source array

A patterned cluster of sources (guns or vibrators) activated together so their wavefields constructively reinforce vertically and attenuate horizontally traveling noise.

See: Source arrays underwater

swath

A subset of receiver lines recorded together as the source crosses the patch; surveys are acquired swath by swath until the full area is covered.

sweep

The frequency-modulated signal emitted by a vibroseis source over several seconds, designed to span a target bandwidth with controlled amplitude.

template

The geometry of active receivers around a shot, the rolling subset of channels that record each source activation in a land 3D survey.

See: Inline / crossline templates, Rock-physics templates: reading rocks in elastic space

vibroseis

A land seismic source that emits a long-duration frequency-modulated sweep, later cross-correlated with the pilot signal to compress the wavetrain into a short wavelet.

See: Vibroseis: sweeps and distortion, Vibroseis deployment in practice