1. Earthquakes & Volcanoes

2. What are Faults?
Fractures (a break) in the earth's crust that can be large or small.
Caused by stress in the rock due to moving tectonic plates.
Usually occur at or near plate boundaries.

3. Three Kinds of Faults Types of Faults Normal Reverse (Thrust)
Strike-Slip (Transform)
Strike-slip is on land
Transform is under water

4. Types of Faults Normal Faults
Rock moves down- caused by divergent boundaries
Reverse Faults
Rock moves upward- caused by convergent boundaries
Strike-slip faults
Rocks slide past one another in opposite directions- caused by transform boundaries

5. Normal Fault

6. Reverse Fault

7. Strike Slip Fault

8. Strike Slip Fault

9. Earthquakes Caused by movement along a fault.
Occurs mainly at plate boundaries.
Focus or Hypocenter– point under the earth’s surface where an earthquake starts
Epicenter – place on earth’s surface directly above the focus
FAULT

10. Current Earthquakes List

11. Earthquake Waves Types of Waves Seismic Waves: Mechanical energy that
travels through the earth and along the
surface
Seismograph – instrument that
measures earthquake waves
Types of Waves
P-Wave (primary wave) – fastest
Moves back and forth
S-Wave (secondary wave) – slower
Moves up and down
L-Wave and Rayleigh Waves (surface wave) – most dangerous
Moves both back and forth AND side to side

12. Earthquake wave animation
Earthquake waves

13. Tsunamis Also called tidal waves
Large ocean waves caused by an earthquake under the ocean.
Ocean floor moves along a fault creating a wave.
Can also be caused by a landslide under or above the water.
WAVE

14. Tsunami Videos
Japanese Tsunami 3/11/2011 Traffic Camera

15. Volcanoes An opening in the earth that erupts gases, ash and lava.
Caused by plate movement along boundaries.
Occur at both divergent and convergent plate boundaries.
Magma - melted rock under the surface (INSIDE)
Lava – Melted rock above the surface (OUTSIDE)
LAVA
MAGMA

16. Many Kinds of volcanoes
Volcanoes vary in shape and composition based on how they erupt and what materials they erupt.
Magmas that have higher silca content tend to be more viscous and will erupt violently as dissolved gasses in the lava build up pressure and then escape all at once.
Magmas that have lower silca content tend to be more fluid, allowing the dissolved gases to escape more readily, resulting in more gentle eruptions.

17. Types of Volcanoes
Shield – rounded volcanic mound made up of layers of hardened lava- gentle eruptions
Cinder cone –volcanic cone made up of rock particles, dust and ash. Violent eruptions
Composite –steep volcanic cone made up of alternating layers of lava and rock particles- violent eruptions.

18. Shield Volcano

19. Cinder Cone Volcano

20. Composite Volcano

21. The Ring of Fire!
An area surrounding the Pacific plate containing many volcanoes, and with high amounts of volcanic activity.

23. Earthquakes and volcanoes
What are some similarities between earthquakes and volcanoes?
What are some differences?