1. Earthquakes!!!!!!!!!

2. Have you ever felt the Earth move under your feet?
Many people have!!
Every day, somewhere on this planet, an earthquake is happening

3. What is an earthquake?
An earthquake is the shaking of the ground caused by rock shifting along a fault.

4. Locations Most earthquakes occur near the edges of tectonic plates.
Tectonic plates move in different directions and at different speeds
As a result of these movements, faults occur.

5. Locations Earthquakes occur along faults because of sliding.
Ring of Fire!
Redo to include that earthquakes occur at all types of boundaries, but most frequently transform

6. Locations --- Epicenter
The epicenter is the point on the Earth’s surface directly above the earthquake’s starting point.
The focus is the point inside the Earth where the quake begins

7. What causes Earthquakes?
Increased stress along faults near the edges of plates
This cause the collision, division, sliding of the plates
As a result, the rock in the plates deform.

8. Causes --- Rocks along fault lines deform in two main ways
Plastic Deformation
Elastic Deformation
Rock moves like modeling clay.
Will take new shapes
Does not break
Does not lead to earthquakes
While rock can stretch further than steel, it does have a breaking point
When the rock breaks, it releases a tremendous amount of energy
When the rock breaks, the broken pieces return to their un-stretched shape.
This sudden return of elastically deformed rock to its original shape is called elastic rebound.
Causes --- Rocks along fault lines deform in two main ways

9. Causes ---Elastic Rebound
During elastic rebound, energy is released.
Some of this energy travels as seismic waves.
The seismic waves cause earthquakes!

10. How do waves travel?
Waves that travel through the Earth are called seismic waves.
Seismic waves that travel through the Earth’s interior are called body waves.
There are two types of body waves: P-Waves, and S-Waves

11. Two types of waves --- P-Waves
“P”ressure waves
“P”rimary waves
Travel through solids, liquids and gasses
Fastest seismic waves
Travel ahead of other seismic waves
Move back and forth, which squeezes and stretches rock,

12. Two types of waves --- S-waves
“S”urface waves,
“S” hear waves
When rock is deformed from side to side, and after it is deformed, it springs back to its original position and S waves result.
Travel through solids
Most destructive!!!!

13. How are Earthquakes Measured?
How do seismologists know when and where earthquakes begin?
How do seismologists know how strong an earthquake was?
Can seismologist predict where and when a future earthquake may take place?

14. Locating Earthquakes
Seismologists use instruments called seismographs to measure earthquakes
Seismographs are located at or near the Earth’s surface and record seismic waves.
When seismic waves reach a seismograph, a seismogram is created
A seismogram is a tracing of an earthquake in motion.

15. Time and Location of earthquakes
Seismologists use seismograms to figure out when earthquakes begin.
They also use seismograms to find out an earthquake’s epicenter.

16. Measuring an earthquake’s strength
Seismograms can also find out an earthquake’s strength!
There are two scales for determining an earthquake’s power
Richter Scale
Modified Mercalli scale

17. Richter scale A scale for measuring power from 1-10
Developed by Charles Richter in 1935 (modified in 1977)
Measures the ground motion of the earthquakes

18. Modified Mercalli scale
A scale from I-XII(1-12)is used to measure the damage and effect an earthquake has on the people.