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.

TWT (s)

Required number in s. Two-way time thickness.

V_int (m/s)

Required number in m/s. Interval velocity.

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

Layer thickness from normal-incidence two-way time and interval velocity. Inputs are interpreted exactly in the displayed units and the calculation returns the following fields without presentation rounding.

h (m)

Returned number in m. Layer thickness.

• 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.
• TWT must be at least 0.
• V_int 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.

• Velocity Model Layer Cake Two Way Time Depth Converter

  Depth from two-way time through a layer-cake velocity model.

• Borehole PS Logging Average Velocity Calculator

  Interval and average shear velocities from downhole first-arrival times at two depths.

• Depth Conversion Average Velocity Method Calculator

  Convert an event's one-way time to depth with a constant average velocity.