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.

ℓ_j

Required list. Ray segment lengths crossing the cell.

a (km)

Required number in km. Cell edge length.

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

Cell hit density: total ray-path length inside the cell divided by cell size. Inputs are interpreted exactly in the displayed units and the calculation returns the following fields without presentation rounding.

L (km)

Returned number in km. Total ray length in the cell.

L/a

Returned number. Dimensionless ray density.

Resolved?

Returned boolean. Whether density exceeds the resolution threshold.

• 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.
• a 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.

• Spatial Grid Cell Count Density Summary

  Bin event eastings/northings into a square grid and report cell occupancy statistics.

• ADC Clip Level Full Scale Counts Calculator

  Digitizer LSB size and clip voltage from bit depth and full-scale range.

• Aftershock Zone Length Utsu Scaling Calculator

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