Seismic Resolution and the Quarter Wavelength Rule

Reference

A seismic wave cannot see beds much thinner than a quarter of its wavelength, and this single rule sets the resolution budget of every survey.

The equation

λ = V / f, tuning thickness = λ / 4
  • λ is wavelength in meters
  • V is interval velocity, f is dominant frequency
  • Below tuning, beds thin without separating on the section

Worked example

At 3000 meters per second and 30 hertz, the wavelength is 100 meters and vertical resolution is about 25 meters. A 10 meter reservoir sand at that depth is a single composite reflection, not a top and a base.

When to use it

Explains why resolution dies with depth: velocity climbs while frequency falls. When a target sits below tuning, thickness must come from amplitude and tuning analysis rather than picking two horizons.

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