Inside Earth (pp. 54 – 61)
Section 2.1
Definitions
Earthquake
The shaking and trembling that results from the movement of rocks beneath the Earth’s
surface
Stress
A force that acts on rocks to change their shape or volume
Shearing
Stress that pushes a mass of rock in two opposite directions
Tension
Stress that stretches rock so that it becomes thinner in the middle
Compression
Stress that squeezes rock until it folds or breaks
Deformation
Any change in the volume or shape of the earth’s crust
Inside Earth (pp. 54 – 61)
Section 2.1
Definitions:
Fault
A break in earth’s crust where slabs of crust slip past each other
Fold
A bend in rock that forms where part of the earth’s crust is compressed
Anticline
An upward fold in rock formed by compression in earth’s crust
Syncline
An downward fold in rock formed by compression in earth’s crust
Plateau
A large area of flat lands elevated high above sea level
Inside Earth (pp. 54 – 61)
Section 2.1
Matching (there can be more than one answer)
1. ______B________ This fault is the result of compression.
A
2. _______A________ This fault is the result of shearing
3. _______C_________This fault is the result of tension.
4. _______C_________This fault occurs when there is little up or
down motion.
B
5. _______A________ This fault has a hanging wall and a foot wall.
6. ______B_______ This fault occurs when two plates move
toward each other.
7. _______A________ This fault occurs when two plates move away
from each other.
C
8. ________C_________This fault occurs when two plates move in
opposite directions.
Inside Earth (pp. 54 – 61)
Section 2.1
Matching
A
Match each of the following pictures to the description
1.
Two rocks are moving past each other in a strike
slip
fault. You can see the lines used to be straight, but are now
curved. The dark line in the rock is the fault line.
B
B
2.
This is the result of a reverse fault. The rock that
makes up the mountain was thrust up and over
another rock.
b
A
C
3. This rock was under enormous pressure from
compression. The rock did not break, buy you can
see how the rock bent by observing the wavy lines.
D
E
4.
Folding created this hill.
C
5. These mountains were created by a normal fault.
As the rocks moved away from each other, a center
piece “fell” downward.
D
E
Inside Earth (pp. 64 – 69)
Section 2.2
Definitions
Focus
The point beneath earth’s surface where rock breaks under stress and causes an earthquake
Epicenter
The point on earth’s surface directly above and earthquake’s focus
Seismic wave
A vibration that travels through earth carrying the energy released during an earthquake
P wave
“primary wave” the type of seismic wave that arrives first and compresses and expands the
ground.
S Wave
“secondary wave” the type of seismic wave that arrives second and moves the ground up and
down or side to side
Surface waves
A type of seismic wave that forms when both P and S waves reach the surface
Inside Earth (pp. 64 – 69)
Section 2.2
Definitions
Seismic waves
A vibration that travels through earth carrying energy released during an earthquake
Magnitude
The measurement of an earthquake’s strength based on seismic waves and movement along faults
Mercali scale
A scale that rates earthquakes according o their intensity and how much damage they cause
Richter scale
A scale that rates seismic waves as measured by a particular type of mechanical seismograph
Moment magnitude scale
A scale that rates earthquake strength by estimating the total energy released by an earthquake
Inside Earth (pp. 64 – 69)
Section 2.2
Fill in the blank.
1. Every day there are about _______8,000_________ earthquakes all over the world.
2. An earthquake produces two types of waves. The _______P__________ wave is the first to
arrive.
The ____S_______ wave moves side to side as well as up and down.
3. ___P_______ waves travel through both solids and liquids.
4. ___S_______ waves cannot move through liquids.
5. Today, the _________Moment Magnitude________________ scale is the scale most commonly
used to report earthquake strength.
Matching
______B________ Mercali Scale
a. measures ground movement
______A________ Richter Scale
b. measured damage
______C________ Moment Magnitude Scale
c. measures the total energy released
Discussion
Why did scientists stop using the Richter scale and adopt the moment magnitude scale?
The Richter scale did not work well for large or distant earthquakes.
Inside Earth (pp. 72 – 77)
Section 2.3
Definitions
Liquefaction
The process why which an earthquakes violent shaking turns normally solid earth into a liquid
Aftershock
An earthquake that occurs after a larger earthquake in the same area
tsunami
a large wave produced by an earthquake on the ocean floor
Inside Earth (pp. 72 – 77)
Section 2.3
1. List four things that can be done to make a home safer in an earthquake.
1. Secure brick chimneys with light metal brackets.
2. In the attic, nail plywood to the ceiling joinsts around the chimney for protection against
falling bricks.
3. Remove heavy items from the walls above beds. Locate beds away from plate glass
windows.
4. Use plywood panels to strengthen the walls that surround the crawl space beneath a house.
5. Bolt the house to its concrete foundation to prevent it from slipping off.
6. To help the house withstand shaking, use metal connecters to strengthen joints in the
house’s frame.
7. To reduce the risk of fire, strap the water heater to the wall to prevent it from toppling over
and breaking a gas line. Learn how to shut off the gas, water, and electricity.
8. To prevent bookshelves, cabinets, and tall dressers from toppling, fasten them to wall studs
with L shaped brackets.
2. Describe safety measures you should take to protect yourself in an earthquake.
Drop, cover and hold to protect yourself. Crouch beneath a sturdy table or desk and hold
on to it so it doesn’t jiggle away during the shaking. If no desk or table is available, crouch against
an inner wall, away from the outside of a building and cover your head and neck with your arms.
Avoid windows, mirrors, wall hangings, and furniture that might topple.
If you are outside, move to an open area. Avoid vehicles, power lines, trees, and buildings. Sit
down to avoid being thrown down.
Keep an emergency kit with food, water, and medical supplies where it is easy to reach.
Inside Earth (pp. 78 – 85)
Section 2.4
Fill in the blank
1. Scientists measure __________stress and deformation_____________ along a fault in order to try
to understand earthquakes.
2. Earthquakes almost always strike ________without warning________________.
Discussion
1. Name and describe 3 meters that measure fault movement.
1. creep meter – a wire stretched across with a fault with a weight on one end.
2. Tilt meter – two bulbs are connected with water in them. If the land tilts the water flows to
one side.
3. Laser-ranging device - a laser is on one side of a fault and a laser reflector is on the other
side. The device calculates any change in time needed for the laser beam to travel to a
reflector and bounce back.
2. How do scientists use satellites to collect data on earthquake faults?
Satellite monitors – satellites equipped with radar make images of the faults by bouncing
radio waves off the ground and recording their echo. The distance from the ground to the
satellite changes with every change in the ground surface. Geologists can detect small
changes in the elevation of a fault by comparing images taken over time.