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.

t_last

Required number. Year of the most recent event.

TR (yr)

Required number in yr. Mean recurrence interval.

now

Required number. Reference year for elapsed time.

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

Compare elapsed time since the last segment rupture against the mean recurrence interval. Inputs are interpreted exactly in the displayed units and the calculation returns the following fields without presentation rounding.

te (yr)

Returned number in yr. Years since the last event.

te/TR

Returned number. Elapsed fraction of a mean cycle.

Status

Returned string. Early/mid/late in the seismic cycle.

• 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.
• TR 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.

• Nearest Neighbor Space Time Linkage Distance

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

• Recurrence Interval Slip Rate Event Slip Calculator

  Characteristic recurrence from per-event slip and long-term slip rate: T = D/V.

• Slip vs Time Predictable Checker

  Check whether observed recurrence interval and slip are consistent with a loading-rate-driven recurrence model.