What is a sudden and violent shaking of the ground, as a result of movements within the earth's crust?

What is the focus of the earthquake?

What is the point on the Earth’s surface, directly above the focus?

What are earthquake waves sent out from the focus that cause the ground to shake?

_______________ waves are the kind of seismic waves that go back and forth.

___________ waves are the seismic waves that go up and down.

What word describes the number of waves that pass a given point at a certain amount of time?

What are parallel, horizontal beam set from wall to wall to support the boards of a floor or ceiling on a tower?

What is the outer layer of earth's structure?

What is the middle layer of earth composed of magma (molten rock)?

What is the inner layer, or the center, of the earth?

What are the slabs of rock in the Earth’s crust that move slowly on the mantle?