Name: ____________________________________
Date: ________________ Period: ___________
Earthquakes and Volcanoes Study Guide
1. What is stress?
A force that acts on a rock to change its shape or volume
2. Which type of seismic wave arrives first at a seismograph?
P-waves
3. What is a focus?
the point beneath Earth’s surface where the crust breaks and triggers an earthquake
4. What is an epicenter?
the point on Earth’s surface that is directly above an earthquake’s focus
5. What is a fault?
A break in the crust where slabs slip past each other
6. What is a seismograph?
An instrument used to measure and record ground movements during an earthquake
7. What is a hot spot?
An area where magma melts through the crust in the middle of a plate
8. Inside a volcano, magma collects in a pocket called magma chamber.
9. A volcano that is erupting or has shown signs that it may erupt in the future is called active.
10. What is magma?
The molten mixture of rock-forming substances, gases, and water deep in Earth’s mantle
11. What causes tsunamis?
water displaced by an undersea earthquake
12. What causes magma to be thicker?
The amount of silica the magma contains
13. What are the three types of stress?
Compression, tension, and shearing
14. What do geologists use to locate an earthquake’s epicenter?
Seismic waves
15. What is the moment magnitude scale?
A rating system that estimates the total energy released by an earthquake
16. What is the point on Earth’s surface that is directly above an earthquake’s focus called?
Epicenter
Name: ____________________________________
Date: ________________ Period: ___________
17. What is the Ring of Fire?
A belt of volcanoes around the rim of the Pacific Ocean
18. Where does molten rock and gas leave a volcano?
vent
19. Is the liquid magma that flows upward through the crust more or less dense than the solid
material around it?
less
20. Explain why ash, cinders, and bombs are produced only in explosive eruptions, not in quiet
eruptions.
Ash, cinder, and bombs are produced in explosive eruptions. In an explosive eruption, the
magma inside the volcano is high in silica. This causes the magma to be thick and gasses get
trapped inside the volcano. As the gasses build the volcano violently erupts creating lots of
ash and cinder.