Earthquake Epicentre Distance Calculator

What this tool does

P waves travel faster than S waves, so the further away the quake, the wider the gap between the two arrivals — the same trick as counting seconds between lightning and thunder. One station gives a distance but not a direction; three stations, and the circles intersect at the epicentre. Wave speeds vary with rock and depth, so these defaults are crustal averages.

Formula

d = Δt(S−P) × (PV × Vs) ÷ (PV − Vs)

Variables

Worked example

Limitations

• The result is an estimate based only on the values you type. Real situations often include factors this calculator does not know about.
• The default values are typical reference figures, not measurements of your situation. Replace them with your own data whenever you have it.
• The formula assumes ideal conditions: no friction losses, no air resistance and no efficiency losses unless you enter them.