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.

A₀/Ā

Required number. Peak amplitude over low-frequency median.

σ_f% (%)

Required number in %. Window scatter of peak frequency.

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

SESAME-style screening: amplitude prominence plus window-to-window frequency stability. Inputs are interpreted exactly in the displayed units and the calculation returns the following fields without presentation rounding.

Clear

Returned boolean. Whether both SESAME-style criteria pass.

Failed

Returned list. Names of failed criteria.

• 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.
• A₀/Ā must be at least 0.
• σ_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.

• Brune Displacement Spectrum Peak Frequency Note

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

• HVSR Nakamura Peak Frequency Calculator

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

• Tidal Stress Phase Trigger Checker

  Check whether an event's tidal phase falls in the promoting window for its fault style.