1. Earthquakes

2. Earthquakes Facts Stress builds up in the cracks in the ground
Shaking and trembling of the earth’s crust.
Is an EVENT not a FORMATION on earth!
Stress builds up in the cracks in the ground
When the rock boundaries slips/gives it releases energy!
The waves travel in all directions
More than 1,000,000 quakes occur a year
Earthquakes continue until all the energy is used up

3. Earthquakes Parts EPI CENTER- FOCUS- underground point of origin
“EPI” means outer
Point ABOVE where quake starts (focus)
most violent shaking occurs here!
Energy travels from focus
FOCUS- underground point of origin
The three main types of seismic waves are: P, S, & Surface (L) waves

4. Earthquakes Waves P Waves
Primary waves
Arrive first at the epicenter
Can travel through solids, liquids, & gases
They are push-pull waves
Travel in straight line

5. Earthquakes Waves S Waves
Secondary waves
Can travel through solids, but NOT through liquids & gases
Move in up-down motion

6. Earthquakes Waves L Waves
Surface (Land) waves
Slowest moving seismic waves
Travel on top of Earth’s surface
Cause most of damage to Earth
bend & twist the surface

7. Seismo-- Seismic wave-earthquake waves Seismo graph-measures
and detects seismic waves
Seismo gram- Paper record of waves
Seismo logist- scientist who study earthquakes

8. How bad was the Quake?? Mercalli Scale Richter Scale
a scale that determines intensity of quake based upon people, damage, & loss
12 levels measured on amount of damage caused
Richter Scale
a scale that determines intensity of Seismic waves
10 levels measured on amount of damage caused
Above a 6 is very destructive

9. Ring of Fire
an area of frequent earthquakes & volcanic eruptions surrounding the Pacific Ocean.

10. 90% of the world's earthquakes occur along the Ring of Fire.
40,000 km horseshoe shape
The Ring of Fire has
452 volcanoes
90% of the world's earthquakes occur along the Ring of Fire.