Use this seismology calculation to reproduce a stated convention, screen observations, or compare scenarios whose units, coordinate conventions, catalog selection, and model assumptions are known.

β (km/s)

Optional number in km/s. Shear-wave velocity at the source.

Δσ (bar)

Required number in bar. Stress drop Δσ in bar.

M₀ (dyn·cm)

Required number in dyn·cm. Seismic moment M₀ in dyn·cm (1 N·m = 1e7 dyn·cm).

The cited overview of Seismology supplies background for the terminology and domain context used by this tool.^[1]

Compute the Brune (1970) circular-crack corner frequency fc = 4.9e6·β·(Δσ/M₀)^(1/3) with β in km/s, Δσ in bar, and M₀ in dyn·cm. Inputs are interpreted exactly in the displayed units and the calculation returns the following fields without presentation rounding.

f_c (Hz)

Returned number in Hz. Corner frequency of the source spectrum.

• Earth structure, source geometry, path effects, site response, instrument response, catalog completeness, uncertainty, and the fitted range can dominate the accuracy of simplified seismic calculations.
• β must be at least 0.
• Δσ must be at least 0.
• M₀ must be at least 0.
• Use finite inputs in the displayed units, preserve source measurements and assumptions, and independently verify consequential decisions.

For analysis or hazard decisions, retain uncertainty and provenance and compare the result with waveform processing, calibrated regional models, and guidance from qualified seismologists or the responsible agency.

• Brune Displacement Spectrum Peak Frequency Note

  For the Brune model, displacement amplitude peaks exactly at the corner frequency.

• Brune Source Time Duration From Corner Calculator

  Characteristic source duration from the Brune corner frequency: τ_c ≈ 1/(2π f_c).

• Moment From Spectral Flat Level Calculator

  Compute seismic moment from the low-frequency spectral plateau Ω₀ using the Brune spectral model.