What is the place called where the movement begins in an earthquake?
focus
100
What is the machine called that detects, measures, and records the energy of earthquake vibrations?
seismograph
100
What is the break in Earth's outer layer caused by the movement of rock plates called?
a fault
100
What can cause rocks in the outer layer of Earth to break?
pressure
200
Part 1: Why can't scientist study Earth's interior by digging holes?
Part 2: How do scientists study Earth's interior?
Scientists can't dig deep enough to even get through Earth's outer layer.
Scientists learn about Earth's interior by studying earthquakes.
200
Approximately what is the distance from the surface to the center of the Earth?
4,000 miles (or 6,400 kilometers)
200
In what direction do seismic waves travel?
Seismic waves from the focus outward in all directions.
200
What is the printed record on a seismograph called?
seismogram
200
What is another name for a "P" wave?
primary wave
300
What is another name for an "S" wave?
Secondary wave
300
What are the four layers of Earth, from surface to the center?
crust, mantle, outer core, inner core
300
Which of the layers is the thickest?
mantle
300
Which of the layers is the thinnest?
crust
300
What is another name for an L (long) wave?
surface wave
400
What is the outermost layer made of?
solid rock
400
Which of the layers is a liquid layer?
outer core
400
Why is it important to study earthquakes?
The information may help warn people of a possible earthquake.
400
Which layer is a sphere of solid material?
inner core
400
What is the outer core probably made of?
melted iron
500
Where is the deepest part of the Earth's crust?
Where is the thinnest part of the Earth's crust?
The deepest part is under the continents.
The thickest part is under the oceans.
500
Besides a seismograph, what are two other instruments used to predict when earthquakes might occur?
Name 2: gravity meter (tells rise and fall of land surface)
strain meter (tells how much rocks expand and contract)
tilt meter (measures changes in the tilt of the Earth)
creep meter (measures how much the land moves along a fault.
500
What type of wave causes the most damage from an earthquake?
surface wave
500
Through what types of materials can primary waves travel?
solids, liquids, gases
500
Which wave is the fastest wave?
Which wave is the slowest wave?
Primary waves are the fastest.
Surface waves are the slowest.