1. Earthquakes

2. Do Now: Take out your homework
Do Now: Take out your homework. Using complete sentences, answer the following questions in your science notebook
What are earthquakes?
Deep earthquakes occur where plates collide along convergent plate boundaries
Earthquakes are vibrations in the ground that result from movement along faults in Earth’s lithosphere
5. Where are shallow earthquakes found?
2. Where do most earthquakes occur?
Shallow earthquakes occur where plates separate along a divergent plate boundary
Most earthquakes occur in the middle of the oceans and along the edges of continents
6. What is a fault?
3. What causes earthquakes?
A fault is a break in Earth’s lithosphere where one block of rock moves toward, away from, or past another
The buildup and release of stress along active plate boundaries causes earthquakes
4. Where do the deepest earthquakes occur?

3. Homework Review: What is an earthquake?
Strike-slip
F; normal
Normal
F; reverse
Reverse T
F; active
F; convergent
F; strike-slip

4. Earthquakes
Objectives: Students will be able to define an earthquake, describe where earthquakes occur, and describe how scientists monitor earthquake activity.
Standards: SC.7.E.6.5, SC.7.E.6.7, SC.7.N.1.3, SC.7.N.1.5, SC.7.N.1.6

5. Essential Questions (copy these down)
What is an earthquake?
Where do earthquakes occur?
How do scientists monitor earthquake activity?

6. Faults Rock deformation can result in ground displacement.
A fault is a crack or a fracture in Earth’s lithosphere along which movement occurs.
Falla: grieta o fractura en la litosfera de la Tierra en la cual ocurre el movimiento.
When rocks move in any direction along a fault, an earthquake occurs.

7. Types of Faults
Strike-slip fault: Two blocks of rock slide horizontally past each other in opposite directions.
Location: transform plate boundary

8. Types of Faults
Normal fault: forces pull two blocks of rock apart. One block moves down along the fault relative to the other.
Location: divergent plate boundaries

9. Types of Faults
Reverse fault: forces push two blocks of rock together. One block moves up along the fault relative to the other.
Location: convergent plate boundaries.

10. Types of Faults

11. Parts of an earthquake
When rocks move along a fault, they release seismic waves: energy that travels as vibrations on and in Earth.
Onda sismica: energia que viaja en forma de vibraciones por encima y dentro de la Tierra.
Focus: a location inside Earth where seismic waves originate and rocks first move along a fault and from which seismic waves originate.
Foco: lugar en el interior de la Tierra donde se originan las ondas sismicas, las cuales son producidas por el movimiento de las rocas a lo largo de un falla.

12. Parts of an earthquake
Epicenter: the location on Earth’s surface directly above the earthquake’s focus.
epicentro: lugar en la superficie de la Tierra justo encima del foco de un terremoto.

13. Seismic Waves
During an earthquake, a rapid release of energy along a fault produces seismic waves, similar to dropping a stone into water.
Seismic waves transfer energy through the ground and produce motion that you feel during an earthquake.

14. Seismic Waves
When an earthquake occurs, particles in the ground can move back and forth, up and down, or in an elliptical motion.
Scientists use wave motion, wave speed, and the type of material that the waves travel through to classify seismic waves.
The three types of seismic waves are primary waves, secondary waves, and surface waves.

15. Rock particles vibrate in same direction waves travel
Primary waves: also called P-waves, a type of seismic wave which cause particles in the ground to move in a push-pull motion similar to a coiled spring.
Onda primaria (tambien, onda P): tipo de onda sismica que causa un movimiento de atraccion y repulsion en las particulas del suelo, similar a un resorte.
Rock particles vibrate in same direction waves travel
Fastest seismic waves
First to be detected and recorded
Travel through solids and liquids

16. Rock particles vibrate perpendicular to direction waves travel
Secondary wave:, also called S-wave, a type of seismic wave that causes particles to move at right angles relative to the direction the wave travels
Onda secundaria (tambien, onda S): tipo de onda sismica que causa que las particulas se muevan en angulos rectos respecto a la direccion en que la onda viaja.
Rock particles vibrate perpendicular to direction waves travel
Slower than P-waves, but faster than surface waves
Only travel through solids

17. Generally cause the most damage at Earth’s surface.
Surface wave: a type of seismic wave that causes particles in the ground to move up and down in a rolling motion.
Onda superficial: tipo de onda sismica que causa un movimiento de rodamiento hacia arriba y hacia debajo de las particular en el suelo.
Rock particles move in a rolling or elliptical motion in the same direction as waves travel.
Slowest seismic wave
Generally cause the most damage at Earth’s surface.

18. Activity: Human Wave Students will be numbered 1-3
1’s: P-waves
2’s: S-waves
3’s: surface waves
In your groups, attempt to model how the waves are travelling through the ground, with each person representing a separate particle.
P-waves:
0:10 at he_classroom
S-waves: 2:00 at aves_in_the_classroom

19. Human Wave Model Limits
Seismic waves only travel outward all directions; not just in one direction like the line of students
Seismic waves also travel at speeds that are much faster, about 3000x faster, than the waves in the Human Wave model
The particle motion of an S wave can be in any direction that is perpendicular to the direction of wave propagation; not just up and down as shown in the demo