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. Seed event magnitude.

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

Reasenberg-cluster linkage parameters (interaction radius and look-ahead time) by magnitude class. Inputs are interpreted exactly in the displayed units and the calculation returns the following fields without presentation rounding.

D₂ (km)

Returned number in km. Cluster interaction radius.

τ (d)

Returned number in d. Look-ahead time for the next linked event.

• 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.

• Gardner Knopoff Declustering Window Lookup

  Gardner-Knopoff space window by mainshock magnitude for catalog declustering.

• Nearest Neighbor Space Time Linkage Distance

  Normalized nearest-neighbor distance for each event against all others.

• Characteristic Earthquake Magnitude Window Lookup

  Estimate characteristic magnitude from a fault length using the Wells & Coppersmith strike-slip relation.