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.

f_i

Required list. Frequency axis samples (ascending).

H/V

Required list. Spectral-ratio amplitudes.

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

Fundamental site frequency from the peak of an H/V spectral-ratio curve. Inputs are interpreted exactly in the displayed units and the calculation returns the following fields without presentation rounding.

f₀ (Hz)

Returned number in Hz. Peak frequency.

A₀

Returned number. Peak H/V amplitude.

• 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.
• 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.

• HVSR Clear Peak Confidence Checker

  SESAME-style screening: amplitude prominence plus window-to-window frequency stability.

• Brune Displacement Spectrum Peak Frequency Note

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

• Damping Response Spectrum Heuristic Scaling

  Heuristic spectral scaling from 5% to another damping ratio: F = (0.05/ζ)^0.25.