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_in (Hz)

Required number in Hz. Input sample rate.

D

Required integer. Integer decimation factor.

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

Validate an integer decimation factor and report the output rate and anti-aliasing guidance. Inputs are interpreted exactly in the displayed units and the calculation returns the following fields without presentation rounding.

f_out (Hz)

Returned number in Hz. Output sample rate.

f_N' (Hz)

Returned number in Hz. Output Nyquist.

Note

Returned string. Anti-aliasing guidance.

• 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.
• f_in must be at least 0.
• D must be at least 1.
• 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.

• Critical Reflection Angle Post Critical Note Checker

  Critical angle for a reflecting interface from velocity contrast, with post-critical guidance.

• Amplification Borcherdt Factor Lookup

  Borcherdt-style short-period amplification factor from NEHRP class.

• Annual Rate To T Years Exceedance Converter

  Convert an annual exceedance rate to the probability of exceeding at least once in T years.