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.

z

Required number. (A_obs − A_mean)/σ statistic.

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

Assess tidal-phase Schuster test significance from the standardized statistic z. Inputs are interpreted exactly in the displayed units and the calculation returns the following fields without presentation rounding.

Level (%)

Returned number in %. Highest one-sided confidence level reached.

Significant?

Returned boolean. Whether the 95 percent threshold is met.

Verdict

Returned string. Interpretation.

• 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.

• Tidal Stress Phase Trigger Checker

  Check whether an event's tidal phase falls in the promoting window for its fault style.

• 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.

• Critical Reflection Angle Post Critical Note Checker

  Critical angle for a reflecting interface from velocity contrast, with post-critical guidance.