What is happening in this
photograph??
What do volcanic eruptions
reveal about the earth’s
interior??
What do you think the darker
material floating on the molten
lava is??
 Objectives:
› Describe what happens during an
earthquake
› Explain the difference between an
earthquake’s focus and epicenter
› Compare and Contrast the three
types of waves produced by
earthquakes
 This Just In ……
› Imagine you are listening to the radio
when the announcer says that a 5.8
earthquake has occurred in Alaska.
› How do earthquakes happen??
› What does the 5.8 mean??




Movements of the
earth’s crust that
occur when ______
_________and release
stored _________
Energy quickly travels
out in ________ from
the point of breakage
Energy can ______ and
________ rock and soil
Most occur at depths
less than ____________
because the rocks are
brittle



Most earthquakes
result from
movements of the
earth’s crust along
___________
Faults are __________
in the earth’s crust
The 2 sides move in
_________ _______
and earthquakes
occur


As the 2 sides of a
fault move past
each other,
sometimes the rocks
________, _______ and
become __________
Tremendous ________
builds up in these
areas

______ _____ – amount
of stress a material
can absorb
› Example – rubber
band stretched too
far


When rocks are
strained beyond
elastic limit – _______
and ________ past
each other
Huge amount of
__________ released.



As rocks break and
move, __________
_______ is transformed
into _______ _________
_______ ________ – the
vibrations produced
by earthquakes
3 Types:
› ____________
› ____________
› ____________



P Waves – _________
seismic waves
_____________ - the
material through
which the wave is
travelling moves in
the _________
direction as the
wave
____________________
_______the earth in
direction of the
wave



S Waves - second
waves to arrive at a
given point – _____
_________
__________ – material
moves at ______
________to the wave
direction
Like the up-anddown movement of
a rope



____________– when
P and S waves arrive
at earth’s surface
Cause the earth’s
surface to __________
____________________
____________________
____________________
Cause the __________
damage during an
earthquake

Earthquakes movie

_______ – area along a
fault where _________
______ ______________ –
where earthquake
begins
› Seismic waves travel
out in __________
from the focus

___________ – point on
earth’s surface directly
__________________ –
strongest shakes felt
here




________________ detect and record
seismic waves
Have a pen attached
to a weight and a
sheet of paper on a
revolving drum
Seismic waves cause
the pen to _______ and
record a wavy line on
paper
_________ of the peaks
indicates the _________
of the earthquake



P, S, and L waves
travel at _________
_________
So, they reach a
seismograph at
__________ _________
The difference
between the arrival
times of the waves
helps scientists find
the _______________



Calculated distance
to the epicenter
becomes the ________
of a circle that is
plotted on a map
Epicenter lies
______________ on the
circle
Plotting circles from
___ ____________
_______ _________
pinpoints the
epicenter – why do
you need 3 stations??

_______ _________–
compares the size of
earthquakes using data
from seismograph
stations
› Each increase of _____
magnitude number
equals an increase of
______ in ground motion
› A magnitude 7
earthquake causes 10
times more damage
than a magnitude 6
and 100 times more
damage than a
magnitude 5

________ ________–
measures the effects
of an earthquake on
›
›
›
›

________________
________________
________________
________________
Data gathered from
people who have
experienced the
quake are used to
determine an intensity
value for their location
Comparing earthquake scales
 Textbook page 136




Most of the world’s
earthquakes occur
along or near the
edges of ________
______________
At these spots, ______
is the greatest
3 Major earthquake
zones:
› 1. ________________
› 2. ________________
› 3. ________________




Accounts for ______ of
world’s seismic activity
Goes all the way
around the _________
_________
Includes east coast of
Asia and west coasts
of North and South
America
Active spots in the U.S.
› __________________
› __________________
Hypothesis – ________________ __________
is being made along the mid-Atlantic
ridge
 This causes many earthquakes


_____________
_________ are
colliding

Causes very
destructive
_____________

Small number of
earthquakes occur
far from plate
boundaries (strong)
› ___________________
___________________
› ___________________
___________________

Even quiet parts of
earth can conceal
large amounts of
____________



1983 – Coalinga, Ca
(between LA and SF)
Magnitude __________
earthquake
Surprised scientists:
› __________________
› __________________
› __________________




Team of scientists
studied what
happened
Found several faults
___________ beneath
They were hidden
inside of __________
in the earth
The determined
these faults are
______ very active
1. Explain what causes earthquakes.
 2. What is the difference between an
earthquake’s focus and epicenter?
 3. How do the 3 types of seismic waves
differ? How are they similar?
 4. Would using 4 seismograph stations to
locate the epicenter of an earthquake
be any more accurate than using 3?
Explain.


Page 139 in Textbook
 Objectives:
› Describe some features produced by
earthquakes
› Discuss factors that determine
earthquake damage
› Explain what causes tsunamis
› Make Inferences about ways to build
structures that could withstand major
damage from earthquakes


Earthquake
evidence is
sometimes
preserved in ________
or ____________
changes to the
ground
Strong earthquakes
leave _________
evidence




At some faults
changes are _____ but
________________ – no
earthquakes
____________ – slow,
continuous, steady
motion
Creep rate of 1
cm/year – ground
levels would be
displaced by 1 meter
after __________
Can break structures




Powerful
earthquakes can
cause ____________
damage
____________
earthquake of 1964
– ______ magnitude
Upheaval of
>260,000 square km
of ground
___________ moved
sideways!

Earthquakes
affect poorly
compacted
sediments more:
› __________
› __________
› __________




Rapid down slope
movements of ________,
________, and _________
Can occur on a _______
or far away
Large sections of
mountain may ________
and race downward
Some continue for
____________, destroying
all in their paths (homes
and roads)


Sudden earth
movements that
_________ ________
Height depends on
the _____ of material
uplifted and the
___________ and
___________ of uplift



Long ________ in rock
or soil
May extend for
_______ _____________
If fissures occur on hill
or mountain –
massive ____________
can occur


____________ of
epicenter to
______________ area
Moderate quake in
a crowded city
causes _________
damage than a
large quake in a
desert



_______ ___ _________
where structures are
built affects amount
of damage
Soft, wet, loose soils
can ___________
seismic waves
Buildings on more
solid ground have
better chance of
survival



Building ________ and
_____________ affect
damage
________ __________
buildings may move
with and withstand
ground motion
Brick and cement
may ________ and
_____________




__________ – an ocean
wave caused by
________________
__________ water –
tsunamis are low and
fast-moving
__________ water –
they slow down and
increase in height (30
meters)
Few structures survive
a large tsunami


Past – changes in
animal behavior and
well levels
Now – seismologists
look at
› __________________
› __________________
› __________________



1981- scientists predict
a quake is likely in the
_____ _______mountains
within ______ years
1988 and 1989 –
moderate quakes
identified as ___________
1989 – devastating
earthquake in _______
___________

If you live near an active fault – should
have an earthquake _______ ________
› What to ______ during quake
› Where to ________ after quake
› How to ______________ if phones don’t work

In earthquake-prone areas – strict
_________ ___ _________ laws are in place
1. What are some changes caused by
earthquakes?
 2. What factors determine the amount of
damage caused by an earthquake?
 3. Describe the hazards you might face if
an earthquake struck while you were:

› asleep in bed
› standing next to a tall building
› at the beach
› skiing

Earthquake Webquest
 Objectives:
› Describe how volcanoes form
› Explain why volcanoes erupt
› Compare the 3 main types of
volcanoes
› Make a model of the structure of a
volcano
 Pressure Is Mounting
› What happens when you blow up a
balloon or inflate a tire and put in too
much air?
› What happens when heat and pressure
build up in a closed space and the
pressure is suddenly released?
› How might these pressure situations be
similar to a volcano that is about to
erupt?



Any opening in the
earth’s crust that has
________ _______ ______
Also, the mountain
that builds up from
_________ _________
Examples:
› _______ – Japan
› ______________ –
Washington state
› _____________ - Sicily



________ (molten rock)
is under great ________
deep inside earth
Magma forms deep
pockets called
________ ___________ in
some places
If the __________ and
_________ are great
enough, magma will
force its way up
through earth’s crust
The more heat and
pressure acting on
magma – the more
likely magma will force
its way to the surface
 _________ – magma
that reaches the
earth’s surface
 __________ – when lava
or other volcanic
materials reach earth’s
surface





___________ – have
erupted in the past
century
___________ –
haven’t erupted in
hundreds of years
___________ –
haven’t erupted in
thousands of years
Eruptive life may
span _________ __
________ ___ ______
Mount Popa Myanmar


_______ ___________ –
formed from large
pockets of magma
When magma is hot
or powerful enough,
it makes its way
toward the surface
through ________ in
the ________



________ – long, nearly
_______ ________ in the
crust through which
magma moves
Can be thousands of
meters long and only a
few meters wide
Magma travels
through the pipe until
it reaches a ________
on earth’s surface


__________ – steep,
hollowed-out area
surrounding a vent
at the _______ of a
volcano
Usually forms after a
very _____________
eruption


________ – opening
through which all
volcanic material
________ ____ _______
Common at the tops
of volcanoes, but
may also be _______
___ ________

Eruptions can be:
› _____________________
_____________________
› _____________________
_____________________

This is determined by:
› __________________
› __________________
› __________________





_________ of lava
that flows from a
vent
Stream can be
_______ or spread out
Some lava flows can
reach speeds of
_________________
Lava cools and
hardens as it moves
Example - __________


Explosive volcanoes
give off ___________
_________
Debris is identified by
____________
› Dust – size of flour
grain
› Ash
› Cinders
› Bombs - > 64 mm


Produced by
different types of
volcanic eruptions
and explosions
Named for its shape
or structure:
› __________________
› __________________
› __________________




Form from the
products of _________
_____________
Ash, cinders, and
other debris mound
up around the vent,
___________ __ ______
Are ________ sloping at
the top and _________
sloping at the base
Usually form from ____,
____________ magma



Have ______, shield
like shapes
Lava is _______ and
______ ______ away
from the vent
As it cools down, it
becomes thicker,
slows down and
collects.



Contain alternating
layers of _________
_____ ____ _______
Usually formed from
_______ ________ of
eruptions
Have ______ tops but
gently ___________
bases



Most earthquakes
and volcanoes
occur along _______
______________
Volcanic activity
can often produce
___________________
As magma moves
up, it may _________
rocks or ___________
overlying crust




Encircles ______________
Major zone of both
_____________ and
_______________
Ocean plates are
______________ and
volcanoes occur in long
chains
One major chain runs
along the west coasts
of _______ _____ _______
_____________





Earth’s _____________
volcanic zones
Plates are moving apart
forming cracks called
___________
As magma rises through
rifts, the _______________
Lava builds up forming
underwater ___________
__________ is formed
from volcanoes that
have risen above the
surface




Develop in parts of
the earth’s mantle
that are _______ _____
They can be _______
from plate boundaries
As the hot spots melt
the surrounding rock,
the rock changes to
_________ and rises to
the surface
_________ ________ are
formed over a hot
spot




________ __________ is
the only active
volcano on the
European mainland
It is located just
outside _______,
_______
It last erupted in ____
Most destructive
eruption was on
August 24, AD. 79



Most people
probably didn’t
know that the
mountain was a
volcano
It hadn’t erupted in
_______________
But there was a
________ earthquake
17 years earlier




Eruption rained hot
ash, mud, and stones
on the residents of
_____________
Many people did not
survive – _______ ______
Town disappeared
completely under
_____ __________of ash
and stone
Wasn’t rediscovered
for ___________ years
How does life develop on
molten rock?
 Moisture from _______ and
______ react chemically with
exposed _________
 Over time, ________ develops
 Wind, waves, and birds scatter
________, ______________ and
_________
 ________ and _________ appear
and break down rock
 Ocean currents bring _________
life
 Eventually there will be a
____________ of plants and
animals

Surtsey, Iceland

Sophisticated devices
can monitor:
› __________
accumulation
› increased __________
activity
› changes in
________________
› gas ____________

Advances in
photography and
satellite imaging
1. What is a volcano? How does it form?
 2. Explain the differences between shield
volcanoes, cinder cones, and composite
volcanoes.
 3. Volcanic activity has been known to
trigger tsunamis. How is this possible?
 4. Draw a general diagram of a volcano.
Label its main parts.


Volcano Webquest

Review sheets – quiz grade