Where did the change begin?
Labs / Geography
Locate the Epicenter
Each station's seismogram records a fast P wave, then a slower S wave. The wider that S − P gap, the farther the quake — so every station draws a circle it must sit on. Drag the three stations and watch the circles cross to fix the epicenter, then flip the reveal to see how close you got.
Labs / Geography / Locate the Epicenter
Locate the Epicenter
Each station's seismogram records a fast P wave, then a slower S wave. The wider that S − P gap, the farther the quake — so every station draws a circle it must sit on. Drag the three stations and watch the circles cross to fix the epicenter, then flip the reveal to see how close you got.
Why it matters
Why explore this?
Geography explains how places, people, and Earth systems affect one another. This model lets you change one factor and watch its effects spread across space.
Explore
Try the model
A —B —C —fix —err —
Investigate
Questions to test
Predict first, try it in the model, then use what you observe to answer.
What to try
- Why does one crossing point of three circles pin down the epicenter, when two circles alone leave you guessing between two spots?
- Drag the stations into a tight cluster. Why does the fix get so much shakier than when they surround the quake?
- Line all three stations up in a row. What happens to the estimate, and why is station geometry as important as the readings themselves?
- Crank up the reading noise. How many kilometres of error does a one-second mistake in the S − P time create?
- Which station shows the smallest S − P gap — and is it always the one closest to the hidden epicenter?
Explain
Make sense of what happened
Connect the pattern to place: identify where the change begins, where its effects appear, and which process links those locations.
Check
Before you leave
What spatial pattern appeared?
Which process connects the cause and effect?
If you can answer all three using evidence from the model, you understand the main idea. If not, return to Explore and change one setting at a time.