Earthquake Distance Calculator
Calculate distance to earthquake epicenter using P and S wave arrival times
About this calculator
The Earthquake Distance Calculator determines how far you are from an earthquake's epicenter by analyzing the time difference between P-wave and S-wave arrivals. P-waves (primary waves) travel faster through the Earth than S-waves (secondary waves), creating a measurable time gap that increases with distance. This tool is essential for seismologists, emergency responders, and curious individuals who want to quickly estimate their proximity to earthquake sources using basic seismographic data.
How to use
Enter the arrival time of the P-wave (first tremor you feel) and the S-wave arrival time (stronger shaking that follows). The calculator uses the time difference and known wave velocities to compute the distance to the earthquake epicenter. Results are typically displayed in kilometers or miles from your location.
Frequently asked questions
What's the difference between P-waves and S-waves?
P-waves are faster compression waves that arrive first, while S-waves are slower shear waves that cause more intense shaking and arrive second.
How accurate is this distance calculation?
The calculation provides a good estimate but can vary due to local geology, wave path variations, and measurement precision of arrival times.
Can I use this without seismographic equipment?
While professional seismographs are most accurate, you can estimate using felt tremors, though results will be less precise than instrumental measurements.