Download Earthquakes

Earthquakes
Forces in Earth’s Crust
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The movement of Earth’s plates creates
enormous forces that _________ or
________ the rock in the crust as if it
were a candy bar.
These forces are examples of
__________, a force that acts on rock to
change its shape or volume.
A rock’s __________ is the amount of
space the rock takes up.
Stress adds __________ to the rock.
Forces in Earth’s Crust
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Types of Stress
 Three different kinds of stress can
occurs in the crust.
 ______________
 ______________
 ______________
 Tension, compression, and shearing
work over __________________ to
change the _________________ of
rock.
Forces in Earth’s Crust
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Tension
 _______________________________
_______________________________
_______________________________
 The __________ on rock is somewhat
like pulling apart a piece of warm
______________.
 Occurs where _________ plates are
moving apart.
Forces in Earth’s Crust
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The stress force called ______________
pulls on the crust, stretching rock so that it
becomes _____________ in the middle.
Forces in Earth’s Crust
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Compression
 _______________________________
_______________________________
_______________________________
 One plate pushing ____________
another can compress rock like a giant
___________________.
Forces in Earth’s Crust
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The stress force called
_______________ squeezes rock until
it folds or breaks.
Forces in Earth’s Crust
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Shearing
 _______________________________
_______________________________.
 Can cause rock to break and slip apart
or to change its shape.
Forces in Earth’s Crust
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Stress that pushes a mass of rock in
two _________________ is called
____________________.
Forces in Earth’s Crust
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Kinds of Faults
 When enough stress builds up in rock,
the rock breaks, creating a fault.
 Recall that a ____________ is a break
in the rock of the crust where rock
surfaces slip past each other.
 The rocks on both sides of a fault can
move up or down or sideways.
Forces in Earth’s Crust
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Kinds of Faults
 Most faults occur along
________________, where the forces
of plate motion push or pull the crust so
much that the crust breaks.
 There are _________ main types of
faults:
 _________________
 _________________
 _________________
Forces in Earth’s Crust
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_____________________
 Tension in Earth’s crust pulls rock
____________.
 _______________________________
_______________________________
_______________________________
 The block that lies _________ is called
the ____________________.
 The rock that lies _________ is called
the ____________________.
Forces in Earth’s Crust
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Normal Faults
 When movement occurs along a normal
fault, the hanging wall slips
___________.
 _______________________________
_______________________________.
 For example, normal faults are found
along the __________________ in
New Mexico, where two pieces of
Earth’s crust are under ____________.
Forces in Earth’s Crust
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_____________ in Earth’s crust pulls rock
apart, causing normal faults. Blue arrows are
the force deforming the crust. Red arrows is
the movement along the fault.
Forces in Earth’s Crust
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_____________________
 In places where the rock of the crust is pushed
together, __________________ causes
______________ faults to form.
 Has the same structure as a
_______________, but the blocks move in the
_______________ direction.
 The rock forming the _____________ of a
reverse fault slides up and over the _________.
 Movement along reverse faults produced part of
the northern ____________________ in the
western United States and Canada.
Forces in Earth’s Crust
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A reverse fault has the same structure as a
_______________, but the blocks move in the
opposite direction.
Forces in Earth’s Crust
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Strike-Slip Faults
 ______________________________________
____________________________________.
 The rocks on either side of the fault slip past
each other sideways, with little up or down
_____________.
 A strike-slip fault that forms the boundary
between two plates is called a
____________________.
 The ______________________ in California is
an example of a strike-slip fault that is a
transform boundary.
Forces in Earth’s Crust
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In a strike-slip fault, the rocks on either side of the
fault slip past each other sideways, with little up
and down motion.
Forces in Earth’s Crust
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The forces produced by the movement of
Earth’s plates can
_______________________________
the crust.
Over millions of years, the forces of plate
movement can change a flat plain into
landforms such as _____________ and
synclines, ________________, faultblock mountains, and _____________.
Forces in Earth’s Crust
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Folding Earth’s Crust
 Sometimes plate movement causes the crust to
______________.
 Rock stressed by ________________ may bend
without ________________.
 Folds are _____________ in the rock that form
when compression shortens and thickens part of
Earth’s crust.
 A fold can be only a few _______________ across
or hundreds of ________________ wide.
 You can often see small folds in the rock exposed
where a ____________ has been cut through a
hillside.
Forces in Earth’s Crust
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Geologists use the terms _____________ and
_____________ to describe upward and downward folds
in rock.
A fold in rock that bends upward into an arch is an
_______________.
A fold in rock that bends downward to form a valley is a
________________.
Anticlines and synclines are found in many places where
__________________ forces have folded the crust.
The central _________________________ in
Pennsylvania are folded mountains made up of anticlines
and synclines.
Forces in Earth’s Crust
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Over millions of years, the forces of plate
movement can change a flat plain into landforms
such as anticlines and synclines, folded
mountains, fault-block mountains, and plateaus.
Forces in Earth’s Crust
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The ___________________ of two plates
cause compression and folding of the
crust over a wide area.
Folding produced some of the world’s
largest __________________________.
The _______________in Asia and the
_________in Europe formed when pieces
of the crust folded during the collision of
two _________________.
Forces in Earth’s Crust
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Stretching Earth’s Crust
 When two normal faults cut through a block
of rock, a ______________________ forms.
 How does this process begins?
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_______________________________________
_______________________________________
_______________________________________
_______________________________________
_______________________________________
_______________________________________
______________________________________.
Forces in Earth’s Crust
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Over millions of years, the forces of plate
movement can change a flat plain into
landforms such as anticlines and synclines,
folded mountains, fault-block mountains, and
plateaus.
Forces in Earth’s Crust
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Uplifting Earth’s Crust
 The forces that raise mountains can also
uplift, or raise, ______________.
 A ___________ is a large area of flat land
elevated high above __________.
 Some plateaus form when forces in Earth’s
_________push up a large, flat
___________ of rock.
 A plateau consists of many _________flat
layers, and is wider than it is tall.
Earthquake and Seismic
Waves
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An ________________ is the shaking
and trembling that results from the
movement of rock beneath Earth’s
surface.
The forces of ___________________
cause earthquakes.
Plate movements produce ___________
in Earth’s ______________, adding
energy to rock and forming faults.
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Earthquake and Seismic
Waves
Stress _________________ along a fault until the
rock breaks.
An earthquake begins.
Most earthquakes begin in the _____________
within about _______ kilometers of Earth’s
surface.
The ___________ is the area beneath Earth’s
surface where rock that is under _________
breaks, triggering an earthquake.
The point on the surface directly above the focus
is called the ______________.
Earthquake and Seismic
Waves
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Types of _________________
 An earthquake produces ____________
called ___________.
 These waves carry __________ as they
travel ______________.
 During an earthquake, seismic waves race
out from the ________ in all directions.
 ________________ are vibrations that travel
through Earth carrying the energy released
during an earthquake.
Earthquake and Seismic Waves
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Seismic waves carry energy from an earthquake away
from the focus, through Earth’s ___________, and
across the ______________.
There are ______ main categories of seismic waves.
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________________
________________
________________
An earthquake sends out ______ types of waves from
its focus:
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____________________________
When these waves reach Earth’s surface at the epicenter,
________________ develop.
Earthquake and Seismic Waves
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Seismic waves carry energy from an
earthquake away from the focus, through
Earth’s interior, and across the surface.
Earthquake and Seismic
Waves
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P waves
 The ____________ waves to arrive are
______________ waves or P waves.
 Seismic waves that compress and
expand the ground like an
_______________.
 ____________________.
Earthquake and Seismic
Waves
Earthquake and Seismic Waves
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___________________
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After P waves come _____________ waves,
or S waves.
Seismic waves that vibrate from
_____________ as well as _____________.
They shake the __________ back and forth.
When they reach the surface, they shake
structures _______________.
Unlike P waves, which travel through both
__________________, S waves cannot
move through ________________.
Earthquake and Seismic Waves
Earthquake and Seismic
Waves
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_______________ Waves
 When P waves and S waves reach the
______________, some of them become
______________ waves.
 Move more __________ than P waves and
S waves, but they can produce
___________________ movements.
 Some make the ground roll like _________
waves.
 Others shake buildings from ___________.
Earthquake and Seismic
Waves
Earthquake and Seismic
Waves
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Measuring Earthquakes
 There are at least _______ different
measures for rating earthquakes, each
with its strengths and short comings.
 ___________ commonly used methods
of measuring earthquakes are:
 ____________________
 ____________________
 ____________________
Earthquake and Seismic
Waves
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The Mercalli Scale
 _______________________________
_______________________________
_______________________________.
 The _____ steps of this scale describe
an earthquake’s effects.
 The same earthquake can have
__________ Mercalli ratings because it
caused different amounts of ground
motion at different locations.
The Mercalli Scale
Earthquake and Seismic
Waves
 ________________________
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An earthquake’s _______________ is a
number that geologists assign to an
earthquake based on the earthquake’s size.
Geologists determine magnitude by
measuring the ____________ and
__________ movement that occur during an
earthquake.
The Richter Scale is a ____________ of an
earthquake’s _____________ based on the
_______ of the earthquake’s seismic waves.
Earthquake and Seismic
Waves
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The seismic waves are measured by a
________________.
A seismograph is an ______________
that ________________ and
_____________ seismic waves.
The Richter scale provides
____________ measurements for
small, nearby earthquakes.
Earthquake and Seismic
Waves
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The ______________________ Scale
 A rating system that _____________
the total energy released by an
earthquake.
 Can be used to rate earthquakes of all
_____________, near or far.
 You may hear news reports that
mention the Richter scale, but the
number they quote is almost always the
moment magnitude for that earthquake.
Earthquake and Seismic
Waves
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To rate an earthquake on the moment
magnitude scale, geologist first study
___________ from seismographs.
The data show what kinds of
__________________ the earthquake
produced and how strong they were.
The data also help geologists ______
how much movement occurred along
the fault and the strength of the rocks
that broke when the fault slipped.
Earthquake and Seismic
Waves
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Comparing Magnitudes
 Earthquake’s _______________ tells
geologists how much ___________
was released by the earthquake.
 Each _______________ increase in
magnitude represents the release of
roughly _________ times more energy.
 The effects of an earthquake
______________ with magnitude.
Earthquake and Seismic
Waves
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Earthquakes with a magnitude below ___
are small and cause ________ damage.
Those with a magnitude between __ and
__ can cause moderate damage.
Earthquakes with a magnitude ______ 6
can cause ________ damage.
The most powerful earthquakes, with a
magnitude of ____ or above, are rare.
Earthquake and Seismic Waves
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Locating the __________________
 Geologists use ____________ waves to
locate an earthquake’s epicenter.
 P waves arrive at a seismograph _______,
with ____ waves following close behind.
 To tell how far the epicenter is from the
seismograph, scientists measure the
_____________ between the arrival times
of the P waves and S waves.
 The ___________ away an earthquake is,
the ___________ the time between the
arrival of the P waves and the S waves.
Earthquake and Seismic
Waves
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Geologists then draw at least three
_____________ using data from different
seismographs set up at ___________ all
over the _____________.
The ____________ of each circle is a
particular seismograph’s location.
The __________ of each circle is the
distance from that seismograph to the
____________.
Monitoring Earthquakes
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The Seismograph
 A _____________ seismograph can
consist of a heavy weight attached to a
frame by a spring or wire.
 Seismic waves cause the
seismograph’s _______ to vibrate. But
the suspend weight with the pen
attached moves very little. Therefore,
the _____ stays in place and records
the drum’s vibrations.
Monitoring Earthquakes
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Measuring Seismic Waves
 In a seismograph, it’s the pen that
remains ______________ while the
paper moves.
 All seismographs make use of a basic
principle of ___________: Whether is it
moving or at rest, every object resists
Monitoring Earthquakes
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Reading a Seismogram
 The pattern of lines, called a
______________, is the record of an
earthquake’s seismic waves produced
by a seismograph.
Monitoring Earthquakes
Monitoring Earthquakes
Monitoring Earthquakes
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How Earthquakes Cause Damage
 When a major earthquake strikes, it can
cause great damage.
 Causes of earthquake damage include
shaking, liquefaction, aftershocks, and
tsunamis.
Earthquake Risk
Monitoring Earthquakes
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Shaking
 Produced by seismic waves can trigger
_______________________________.
 Can also damage or destroy _________ and
________, topple utility _______, and
fracture gas and water _________.
 The types of _______________ determine
where and how much the ground shakes.
 The most ______________ shaking may
occur kilometers away from the epicenter.
 ____________ soil shakes more violently
than _____________ rock.
Monitoring Earthquakes
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__________________
 _______________________________
_______________________________
_______________________________.
 Is likely where the soil is full of
_______________.
 As the ground gives way, buildings
_______ and _______ apart.
Monitoring Earthquakes
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__________________
 Sometimes, buildings weakened by an
earthquake _______________ during
an _________________.
 _______________________________
______________________________.
 May strike ________, __________, or
even ____________ later.
Monitoring Earthquakes
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_______________
 When an earthquake __________ the ocean floor,
_________________ causes the ocean floor to rise
slightly and push water out of its way.
 The water ________________ by the earthquake
may form a large wave.
 Spreads out from an earthquake’s _____________
and _____________ across the ocean.
 As a tsunami approaches ______________ water,
the wave grows into a mountain of water.
Monitoring Earthquakes