Explore the Earthquake & Seismic Wave Laboratory
Trigger a virtual earthquake, watch P, S and surface waves radiate outward, read live seismograph traces at three stations. Works on phones and computers.
- Free to use
- No signup
- Nothing to install
- Runs in your browser
Illustration. Open the tool for the real thing.
See it in action
The Earthquake & Seismic Wave Laboratory with sample data entered and the result showing.
What is the Earthquake & Seismic Wave Laboratory?
Trigger a virtual earthquake, watch P, S and surface waves radiate outward, read live seismograph traces at three stations, and triangulate the epicenter from S−P intervals. It runs in your browser, so a change to a setting or a drag on an object shows up at once.
The USGS and seismic networks worldwide use this exact S−P triangulation technique, now automated, to report earthquake locations within minutes.
3 steps to your result
Open the tool and follow along. Nothing to install.
What you get
P waves travel fastest and arrive first; S waves are slower; surface waves are slowest but usually cause the most damage.
The S−P time interval at a station grows with distance from the epicenter.
Distance (km) ≈ S−P interval (seconds) × 8 is a widely used quick estimate.
Trigger a magnitude 7 earthquake and read the S−P interval at each station.
Convert each interval to a distance and try to triangulate the epicenter on the map.
Change the focal depth and see how it changes arrival times.
Used for
Pick one to see how it fits.
Teachers
For teachers: project the Earthquake & Seismic Wave Laboratory on the board, let students predict the result, then run it together and test this: Convert each interval to a distance and try to triangulate the epicenter on the map. For students: change one thing at a time and write down what changes.
Try it freeHow it compares
A plain look at this tool next to the usual alternative.
| This simulation | Textbook diagram | |
|---|---|---|
| Interactive | Drag, tap and change settings | Fixed picture |
| Install | Nothing to install | Not needed |
| Cost | Free to use | Depends on the book |
Questions people ask
Why do seismologists need at least three stations to locate an epicenter?
One station's S−P interval only gives a distance, forming a circle of possible locations; three circles from three stations intersect at a single point, the epicenter.
Why do surface waves cause the most damage despite arriving last?
They travel only along the Earth's surface, so their energy spreads out in two dimensions instead of three, keeping amplitudes larger over distance.
Is the Earthquake & Seismic Wave Laboratory free to use?
Yes. The Earthquake & Seismic Wave Laboratory is free, needs no signup or download and runs in your web browser. It is part of the Geology group of AZRS simulations.
Does the Earthquake & Seismic Wave Laboratory work on a phone or tablet?
Yes. The Earthquake & Seismic Wave Laboratory takes touch input as well as mouse input, so you can use its 3 adjustable settings with a finger. A larger screen makes the controls and graphs easier to read.
How do I use the Earthquake & Seismic Wave Laboratory?
1. In the Earthquake & Seismic Wave Laboratory, use the controls to change Magnitude, Focal depth, Fault type. The simulation reacts instantly. 2. In the Earthquake & Seismic Wave Laboratory, press "Trigger earthquake", "Reset" to start, reset or change what is happening. 3. Start with this experiment: Trigger a magnitude 7 earthquake and read the S−P interval at each station. Drag any glowing handle, object or slider with your mouse or finger and the Earthquake & Seismic Wave Laboratory responds in real time. 4. Change one setting at a time and watch which readout moves, then compare it with this idea: P waves travel fastest and arrive first; S waves are slower; surface waves are slowest but usually cause the most damage.
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Try the Earthquake & Seismic Wave Laboratory now
Trigger a virtual earthquake, watch P, S and surface waves radiate outward, read live. Free to use.
Try it free