Where did the change begin?
Labs / Geography
Seismic Waves Through Earth
Drag the earthquake around the rim and watch seismic waves race through the planet. Fast waves bend as they cross into the mantle and core, and the S waves vanish across a whole band of the surface — the shadow zone that first told geologists the outer core must be liquid.
Labs / Geography / Seismic Waves Through Earth
Seismic Waves Through Earth
Drag the earthquake around the rim and watch seismic waves race through the planet. Fast waves bend as they cross into the mantle and core, and the S waves vanish across a whole band of the surface — the shadow zone that first told geologists the outer core must be liquid.
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
t 0:00120° station —shadow —CMB 2891 km
Investigate
Questions to test
Predict first, try it in the model, then use what you observe to answer.
What to try
- Switch to S waves only. Why do they never reach the far side of the planet, no matter where you put the quake?
- Now watch P waves. They pass right through the core — so why is there still a gap where no P wave lands?
- Slow the core speed far below the mantle speed. Does the shadow zone grow wider or narrower, and what does that tell you about how sharply rays bend at the boundary?
- The 120° station often reads “no direct arrival.” If you were a geologist in 1906 seeing that on every quake, what would you conclude about the inside of the Earth?
- Move the quake to different spots. Does the width of the shadow zone depend on where the earthquake happens, or only on what the Earth is made of?
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.