Spin, Slip and Surge: teacher key

Natural Disasters, grade 7 edition, written for 7th grade. What makes air spin, rock slip and the sea rise onto land? Scientists measure each one, and some popular ideas turn out to be wrong.

Read the book. Print this page for the key.

Questions and answers

1. What does each whole number up on the magnitude scale mean?
   • A tenfold increase in the measured size of the waves (answer)
   • One more minute of shaking
   • A new kind of earthquake
2. Why is a tsunami not a tidal wave?
   • Tides come from the Sun and Moon, and tsunamis are not related to them (answer)
   • Tsunamis are slower than tides
   • Tsunamis only happen in rivers
3. What helps start the spin in a storm's rising air?
   • Winds moving in different speeds and directions at different heights (answer)
   • A seismometer
   • A creek
4. Where do tornadoes happen in the United States?
   • Only in Tornado Alley
   • All over the country (answer)
   • Only in the mountains
5. How does a tsunami's speed change near land?
   • It gets faster
   • It stays a jet's speed
   • It slows to about the speed of a car (answer)
6. What does a major hurricane mean?
   • Category 3 and higher (answer)
   • Category 1 only
   • Any rainy storm

Words

• magnitude: earthquake size
• tsunami: big ocean wave
• seismometer: shake measurer
• evacuate: leave for safety
• overpasses: road bridges