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.

D (m)

Required number in m. Average slip.

L (km)

Required number in km. Rupture length.

μ (GPa)

Optional number in GPa. Rigidity.

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

First-order stress drop from the strain-drop picture: Δσ ≈ μ·(D/L). Inputs are interpreted exactly in the displayed units and the calculation returns the following fields without presentation rounding.

Δσ (bar)

Returned number in bar. Stress-drop estimate.

D/L

Returned number. Dimensionless strain drop.

• 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.
• D must be at least 0.
• L must be at least 0.
• μ 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.

• Reservoir Induced Stress Change Bar Calculator

  First-order Coulomb stress perturbation under a reservoir load: Δσ ≈ ρ·g·h.

• Tsunami Seafloor Vertical Offset Calculator

  First-order seafloor vertical offset from dip-slip on a fault: u ≈ slip·sin(dip).

• Characteristic Earthquake Magnitude Window Lookup

  Estimate characteristic magnitude from a fault length using the Wells & Coppersmith strike-slip relation.