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.

κ (s)

Required number in s. Site kappa.

f (Hz)

Required number in Hz. Frequency.

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

Site anelastic attenuation factor exp(−π κ f) at a given frequency. Inputs are interpreted exactly in the displayed units and the calculation returns the following fields without presentation rounding.

exp(−πκf)

Returned number. Spectral attenuation factor.

• 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.
• κ must be at least 0.
• f 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.

• Attenuation Quality Factor Q Calculator

  Infer quality factor Q from amplitude decay along a propagation path: A = A₀·exp(−π f x / (Q v)).

• Corner Frequency Stress Drop Consistency Checker

  Invert the Brune relation fc = 0.49·β·(Δσ/M₀)^(1/3) for stress drop Δσ = M₀·(fc/(0.49·β))³ given the moment and compare with a claimed Δσ; no rigidity term is needed because Δσ/M₀ replaces it.

• HVSR Nakamura Peak Frequency Calculator

  Fundamental site frequency from the peak of an H/V spectral-ratio curve.