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. Event magnitude.

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

Classify expected surface-rupture behavior by magnitude band. Inputs are interpreted exactly in the displayed units and the calculation returns the following fields without presentation rounding.

Surfaces?

Returned boolean. Whether surface rupture is expected.

SRL (km)

Returned number in km. Wells-Coppersmith style expected rupture length.

Band

Returned string. Magnitude band classification.

• 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.

• Magnitude Scaling Saturation Check Tool

  Flag whether a rupture length implies magnitude beyond the empirical saturation limit (~M7.8) of simple linear scaling.

• Aftershock Zone Length Utsu Scaling Calculator

  Utsu aftershock-zone scaling: log₁₀L(km) = 0.5·M − 1.8, with equivalent area.

• Array Aperture Moveout Resolution Checker

  Check whether array aperture resolves the expected moveout across the slowness band.