Labs / Geography
Earthquake Magnitude & Shaking
Slide the magnitude and watch the seismogram grow and the building sway. Then drag the seismograph station across the map to move it nearer or farther from the epicenter. The Richter scale is logarithmic, so each step up the scale is a giant leap in ground motion and released energy.
amp —energy —intensity —felt —
What to try
- Step the magnitude from 5 to 6 to 7. The number grows by one each time — but how many times bigger does the released energy get?
- How far away can a magnitude 8 still topple the building, and how close must a magnitude 4 be to be felt at all?
- With the same magnitude and distance, does soft ground shake more or less than hard rock? Why might a city built on a river delta be at greater risk?
- How many tonnes of TNT does a “Great” quake release — and how does that compare to a “Moderate” one?
- Drag the station right to the epicenter. Is there any distance at which a magnitude 2 quake feels dangerous?