Download Chapter 11 Earthquakes and Volcanoes Outline

Chapter 11 Earthquakes and Volcanoes
I. Earthquakes
A. Sudden movement of Earth's crust
1. Shaking
2. Trembling
3. Rising and falling like waves
B. Faulting
1. Most common cause of earthquakes
2. Crust pushed together or pulled apart
3. Energy released
C. Tsunamis
1. Earthquake on ocean floor
2. Giant sea waves
3. Travel 700 to 800 kms/hr
4. Cause great damage
D. Seismic waves
1. Focus
a. Place where rocks break and move
b. Origin of earthquake
2. Epicenter
a. Point directly above focus
b. Place where most violent shaking occurs
3. Three types of waves
a. Primary (P waves)
1.) Travel fastest
2.) Travel through solids, liquids, gases
3.) Push-pull waves
b. Secondary (S waves)
1.) Do not travel as fast as P waves
2.) Travel only through solids
c. Surface (L waves)
1.) Slowest moving
2.) Originate on Earth's surface at epicenter
3.) Travel on surface
4.) Cause most damage
E. Seismograph
1. Detects and measures seismic waves
2. Developed by John Milne in 1893
3. Seismologists
a. Scientist who studies earthquakes
b. Determine a quake's strength by reading - seismogram
4. Richter scale
a. Number scale used to determine a quake's strength
b. Six and above very destructive quake
F. Predicting earthquakes
1. Must include where, when, how strong
2. Could better plan growth of cities
3. Warning signs
a. Changes in seismic waves
b. Slight change in tilt of Earth's surface
c. Rise and fall of land near a fault
d. Water level in wells changes
e. Behavior of certain animals changes
II. Formation of volcano
A. Volcano
1. Magma chamber
a. Deep pocket in Earth
b. Contains magma (hot liquid)
2. Lava
a. Magma on Earth's surface
b. Destroys everything in its path
3. Volcano
a. Area where magma becomes lava
b. Result of volcanic material
c. Has openings called vents
B. Volcanic eruptions
1. Eruptions vary
a. Some quiet
b. Some violent
2. Four types of lava
a. 1st type, dark-colored
1.) Contains a lot of water
2.) Rich in iron and magnesium
b. 2nd type, light in color
1.) Contains little water
2.) Rich in silicon and aluminum
3.) Forms rhyolite, resembles granite
c. 3rd type, combination of dark-colored and light-colored
1.) Forms different varieties of igneous rock
2.) One type - andesite
d. 4th type
1.) Contains large amounts of gases
2.) Forms rocks with many holes
3.) Examples are pumice and scoria
3. Eruptions
a. Volcanic dust
1.) Very fine particles
2.) 0.25 mm in diameter
3.) Carried by wind
b. Volcanic ash
1.) Rock particles more than 0.25 mm and less than 5 mm in diameter
2.) Forms small rocks
3.) Carried by wind
c. Volcanic bombs
1.) Few centimeters to several meters in diameter
2.) Molten when hurled
3.) Cinders - size of golf balls
C. Types of volcanoes
1. Cinder cones
a. Made from cinders and other rock particles
b. Formed from violent explosions or eruptions
c. Cones not high
2. Shield volcanoes
a. Composed of quiet lava flows
b. Forms dome-shaped mountains
3. Composite volcanoes
a. Composed of alternating layers of rock particles and lava
b. Forms from violent eruption first
c. Quiet eruption follows
d. Large cone-shaped mountain forms
D. Volcanic activity
1. Active
a. Erupts continually or periodically
b. Several active ones in U.S.
2. Dormant
a. Once active
b. Now inactive or sleeping
3. Extinct
a. Has not erupted within modern history
b. Worn away to level of magma chamber
III. Volcano and earthquake zones
A. Most occur in 3 zones of world
B. Great deal of movement and activity in Earth's crust
C. Ring of Fire - Pacific Ocean
D. Mediterranean Zone
E. Mid-Atlantic Ridge, Iceland, Atlantic Ocean