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.

M₀ᵢ

Required list. Event seismic moments.

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

Total moment and equivalent single-event magnitude of an event list. Inputs are interpreted exactly in the displayed units and the calculation returns the following fields without presentation rounding.

ΣM₀ (N·m)

Returned number in N·m. Sum of moments.

M_w,eq

Returned number. Magnitude of the summed moment.

N

Returned integer. Number of events.

• 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 Magnitude Type Histogram Summary

  Count catalog magnitudes by reported type (ml, mb, ms, mw, other).

• Declustering Retained Event Fraction Summary

  Fraction of the catalog retained as Poissonian background after declustering.

• Slow Slip Equivalent Magnitude Duration Scaling Calculator

  Equivalent moment magnitude of a slow-slip episode from plate-rate slip accumulated over its duration.