Wave Physics glossary

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

amplitude

In seismic data, the peak signal magnitude of a reflected wavelet; sensitive to acoustic-impedance contrast and pore fluid at the reflector.

See: True-amplitude migration, Trace editing & amplitude recovery

bandwidth

The range of frequencies present in a signal with significant amplitude; broader bandwidth yields sharper, higher-resolution wavelets.

See: Bandwidth & spectral QC, Bandwidth and Resolution

direct arrival

Energy that travels directly from source to receiver along the surface or through water without reflecting off a subsurface interface.

dominant frequency

The peak frequency of a wavelet's amplitude spectrum; together with velocity it sets the vertical resolution via the tuning thickness λ/4.

free-surface multiple

A multiple that includes at least one downward reflection from the air-earth or air-water free surface.

ghost

A short-delay reflection from the free surface immediately above the source or receiver, producing a spectral notch at f = V/(2d).

ground roll

Low-frequency, low-velocity, high-amplitude Rayleigh-wave noise on land seismic records, characterized by linear moveout in shot gathers.

inter-bed multiples

Internal multiples reverberating between two strong intra-formational interfaces; common in layered carbonate or evaporite sequences.

See: Inter-bed multiples & model-based prediction

internal multiple

A multiple whose successive bounces all occur within the subsurface, with no involvement of the free surface; harder to predict than surface multiples.

multiples

Plural of multiple; reflections that have bounced more than once, contaminating primary reflectivity and complicating interpretation.

See: Multiples, Inter-bed multiples & model-based prediction

p-wave

A compressional (primary) elastic wave in which particles oscillate parallel to the propagation direction; the fastest body wave, with velocity Vp = √((K + 4μ/3)/ρ).

See: P-waves and S-waves

primary

A reflection that has bounced exactly once in the subsurface; the signal of interest for imaging the geology.

primary reflections

Singly-reflected events from subsurface interfaces; the desired signal that migration and inversion aim to map.

rayleigh wave

A surface wave with retrograde elliptical particle motion in the vertical plane of propagation; the main carrier of land seismic ground roll.

ricker wavelet

A zero-phase wavelet given by the second derivative of a Gaussian, parameterized by a peak frequency; a standard model in synthetic seismograms.

See: The Ricker Wavelet

s-wave

A shear (secondary) elastic wave in which particles oscillate perpendicular to propagation, with velocity Vs = √(μ/ρ); cannot propagate through fluids.

See: P-waves and S-waves

source signature

The time-domain pulse emitted by a seismic source, including any bubble oscillations or sweep correlation residual; the wavelet before earth filtering.

See: Source signature QC, Source signature measurement & QC

surface wave

An elastic wave that travels along a free surface or interface with amplitude decaying with depth; includes Rayleigh and Love waves.

turning waves

Refracted waves that curve back to the surface due to a positive velocity gradient with depth; exploited by FWI and diving-wave tomography.

water-bottom multiple

A free-surface multiple that bounces between the sea surface and the seafloor, often the strongest multiple in marine data.

wavelet

The short, finite-duration pulse that represents the effective source signature recorded at the receiver; convolves with reflectivity to form a trace.

See: The Wavelet Zoo, The Ricker Wavelet