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.

T (s)

Required number in s. Spectral period.

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

Typical vertical-to-horizontal spectral ratio by period band. Inputs are interpreted exactly in the displayed units and the calculation returns the following fields without presentation rounding.

V/H

Returned number. Vertical/horizontal amplitude ratio.

Band

Returned string. Period band note.

• 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.
• T 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.

• Damping Response Spectrum Heuristic Scaling

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

• DART Pressure Tsunami Flag Checker

  Flag DART bottom-pressure observations whose amplitude and period band match a tsunami signature.

• Geophone Natural Period Response Corner Lookup

  Response corner and usable band for common geophone classes by natural frequency.