Glencoe Chapter 9

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Faults

• Rocks break and move along surfaces called faults.

Earthquakes

• Vibrations caused by breaking of rocks along faults.

Types of Faults

• Normal Faults:– Force: Tension– Direction: Apart

• Reverse Faults– Force: Compression– Direction: Together

• Strike-slip Fault:– Force: Shearing– Direction: Sliding

Normal Faults

Reverse Fault

Strike-Slip Fault

Seismic Waves

• Vibrations caused by earthquakes.

Earthquake Focus

• The point in the Earth’s interior where the is energy release occurs.

Primary Waves:

• Waves that move through Earth by causing particles in rocks to move back and forth in the same direction the wave is traveling.

Secondary Waves

• Move through Earth by causing particles in rocks to move at right angles to the direction of the wave.

Surface Waves

• Move by giving particles an elliptical motion, as well as a back-and-forth swaying motion.

Epicenter

• The point on Earth’s surface directly above an earthquake’s focus.

Locating an Epicenter

1. S-P Interval: Take the difference in arrival time of the primary and secondary waves.

2. Find the distance from the seismic station and the epicenter. For 3 stations.

3. Plot the distances as radii on three circles. Where they meet is where the epicenter is located.

S-P Interval

Find Distance

Plot Epicenter

Seismologist

• Scientist who studies earthquakes.

Seismograph

• Instrument used to measure the vibrations caused by earthquakes

A mile or so below you there are large pieces of the Earth’s crust

known as __________________. Plates

They move and float on a river of ______________ in the Earth’s

_______________. Magma

Mantle

Where these plates break a ______________ will form.

Faults

At ______________ plate boundaries ___________ forces

cause reverse faults to form. Convergent

Compression

At transform plate boundaries __________ forces cause

__________ faults to form. Shearing

Strike-Slip

Lastly, as tension forces act on the plates at

___________________ plate boundaries, __________ faults

form. Divergent

Normal

As plates interact they sometimes produce large

vibrations known as __________. Earthquakes

The _________ is the location under the ground where the energy of the vibrations was

released.

Focus

The point on the surface directly above this location is known as

the ____________. Epicenter

_____________, scientist who study earthquakes use

instruments called _______________ to measure

the vibrations caused by earthquakes.

Seismologist

Seismograph

The first wave of energy released by an earthquake is a

_______________ wave. Primary

P-waves travel in a _________ motion.

Side to Side

Second to arrive at the _________ station is the

____________ wave Seismic

Secondary

These waves travel in a __________ motion.

Up and Down

The seismic wave that causes the most damage is the

________________ wave. Surface

Scientist read _____________ to determine the difference in the arrival time of the ___________ wave and the _____________

wave. Seismograms

P-wave

S-wave

Once they have determined the __________________ they use a

chart to determine the distance the ____________ station was

located from the _______________.

S-P interval

Seismic

Epicenter

The height of the _________ on the paper tells the ___________ of the earthquake. __________

use the _________ scale to measure the magnitude of

earthquakes. Lines

Magnitude

Richter

Because the _______________ waves caused by earthquakes

move out in all directions, scientist must have

measurements from __________ different __________ stations.

Seismic

3

seismic

Once they have the measurements they use a

_____________ and plot the distance as a radius out from

each seismic station.

Map

Where these circles cross the _________________ of the

earthquake is located. Epicenter

If a(n) ____________ takes place under ________________ a _______________ can take

place.

Earthquake

Water

Tsunami

This large wave can reach _________ meters in height.

30

The ___________ plates that make up the earth’s

___________ are on top of the Earth’s ___________.

Tectonic

Crust

Mantle

Below the Mantle is the _________ core and _________

core. Outer Core

Inner Core

The ______ core is composed of _________ and _________ and

is liquid. Outer Core

Iron

Nickel

The _______ core is also composed of __________ and

________ but is solid. Inner

Iron

Nickel

The mantle is made mostly of _______, __________,

_____________ and _________. Magnesium

SiliconOxygen

Iron

______________ ___________ is the boundary between the

crust and mantle Moho Discontinuity

___________ waves speed up because they are passing into

the __________ which is the rigid __________ and upper

______________.

SeismicLithosphere

CrustMantle