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.

M₁

Required number. Lower magnitude anchor.

N₁

Required number. Cumulative count at M₁.

M₂

Required number. Higher magnitude anchor.

N₂

Required number. Cumulative count at M₂.

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

b-value from two cumulative-count anchors of the Gutenberg-Richter law. Inputs are interpreted exactly in the displayed units and the calculation returns the following fields without presentation rounding.

b

Returned number. Gutenberg-Richter b-value.

a

Returned number. Productivity term a (log10 annual count at M=0).

• 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.
• N₁ must be at least 0.
• N₂ must be at least 0.
• 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.

• Gutenberg Richter A Value Annual Normalization

  Annualized GR productivity: a = log₁₀(N_year) + b·Mc.

• Radiated Energy From Magnitude Gutenberg Richter

  Gutenberg-Richter energy relation log₁₀Es(J) = 1.5·M + 4.8.

• Tau-P Travel Time Anchor Interpolation Calculator

  Linearly interpolate P travel time between supplied distance anchors.