Book 5, Question 59
Shake, Rattle and Roll! Why Does Earth Have Earthquakes?
Earth's outer layer is broken into big pieces called plates that move very slowly. Sometimes the edges get stuck, and then they suddenly slip. That sudden slip sends out shaking waves, which we feel as an earthquake.
From the book
Page from A Million Whys Book 5
More fun facts
- Earth's outer layer is made of huge slabs called tectonic plates that drift on the slowly flowing mantle below.
- The plates are always moving slowly, but their edges get stuck because of friction.
- When the stress grows bigger than the friction, the rock suddenly slips and the ground shakes.
- The energy travels as ripples called seismic waves.
- The spot on the surface right above where an earthquake starts is called the epicenter.
- How far away people can feel an earthquake depends on its size, or magnitude.
- California's San Andreas Fault is more than 650 miles long.
Sources: NASA Space Place, U.S. Geological Survey, National Geographic Kids
Questions kids ask
What is a fault?
A fault is a crack in Earth's crust where blocks of rock can slip past each other.