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.

M

Required number. Mainshock magnitude.

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

Gardner-Knopoff space window by mainshock magnitude for catalog declustering. Inputs are interpreted exactly in the displayed units and the calculation returns the following fields without presentation rounding.

R_w (km)

Returned number in km. Space window radius.

T_w (d)

Returned number in d. Time window length.

• 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.

• Catalog Complete Timespan Denominator Checker

  Verify the catalog window is long enough for stable annual-rate denominators.

• Reasenberg Space Time Window Lookup

  Reasenberg-cluster linkage parameters (interaction radius and look-ahead time) by magnitude class.

• B Value Standard Error Shi Bolt Formula

  Shi & Bolt (1982) b-value uncertainty, simplified for unit-variance magnitude residuals: σ_b = 2.30·b²/√(N−1); supply magnitude residuals for the full Σ(Mᵢ−M̄)² form.